query: Gold is resistant to all acids except aqua regia.

pos: Gold Gold is a chemical element with symbol Au ( from aurum ) and atomic number 79 . In its purest form , it is a bright , slightly reddish yellow , dense , soft , malleable , and ductile metal . Chemically , gold is a transition metal and a group 11 element . It is one of the least reactive chemical elements and is solid under standard conditions . Gold often occurs in free elemental ( native ) form , as nuggets or grains , in rocks , in veins , and in alluvial deposits . It occurs in a solid solution series with the native element silver ( as electrum ) and also naturally alloyed with copper and palladium . Less commonly , it occurs in minerals as gold compounds , often with tellurium ( gold tellurides ) .   Gold 's atomic number of 79 makes it one of the higher numbered , naturally occurring elements . It is thought to have been produced in supernova nucleosynthesis , from the collision of neutron stars , and to have been present in the dust from which the Solar System formed . Because the Earth was molten when it was formed , almost all of the gold present in the early Earth probably sank into the planetary core . Therefore , most of the gold that is present today in the Earth 's crust and mantle is thought to have been delivered to Earth later , by asteroid impacts during the Late Heavy Bombardment , about 4 billion years ago .   Gold is resistant to most acids , though it does dissolve in aqua regia , a mixture of nitric acid and hydrochloric acid , which forms a soluble tetrachloroaurate anion . Gold is insoluble in nitric acid , which dissolves silver and base metals , a property that has long been used to refine gold and to confirm the presence of gold in metallic objects , giving rise to the term acid test . Gold also dissolves in alkaline solutions of cyanide , which are used in mining and electroplating . Gold dissolves in mercury , forming amalgam alloys , but this is not a chemical reaction .   Historically , the value of gold was rooted in its relative rarity , easy handling and minting , easy smelting and fabrication , resistance to corrosion and other chemical reactions ( nobility ) and its distinctive color . As a precious metal , gold has been used for coinage , jewelry , and other arts throughout recorded history . In the past , a gold standard was often implemented as a monetary policy , but gold coins ceased to be minted as a circulating currency in the 1930s , and the world gold standard was abandoned for a fiat currency system after 1976 .   A total of 186,700 tonnes of gold is in existence above ground , as of 2015 . The world consumption of new gold produced is about 50 % in jewelry , 40 % in investments , and 10 % in industry . Gold 's high malleability , ductility , resistance to corrosion and most other chemical reactions , and conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices ( its chief industrial use ) . Gold is also used in infrared shielding , colored-glass production , gold leafing , and tooth restoration . Certain gold salts are still used as anti-inflammatories in medicine . As of 2014 , the world 's largest gold producer by far was China with 450 tonnes .

neg: Guar hydroxypropyltrimonium chloride Guar hydroxypropyltrimonium chloride is an organic compound that is a water-soluble quaternary ammonium derivative of guar gum . It gives conditioning properties to shampoos and after-shampoo hair care products . The effects of the cationic charge density , guar concentration in aqueous solution , and treatment time on bleached European hair have been studied . A mechanical testing method has been successfully applied to determine the efficacy of cationic guars to improve the ease of combing . The results were confirmed in a shampoo formulation on both virgin and bleached hair .

neg: Potassium Potassium is a chemical element with symbol K ( derived from Neo-Latin , kalium #Latin ) and atomic number 19 . It was first isolated from potash , the ashes of plants , from which its name derives . In the periodic table , potassium is one of the alkali metals . All of the alkali metals have a single valence electron in the outer electron shell , which is easily removed to create an ion with a positive charge -- a cation , which combines with anions to form salts . Potassium in nature occurs only in ionic salts . Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and reacts vigorously with water , generating sufficient heat to ignite hydrogen emitted in the reaction and burning with a lilac-colored flame . It is found dissolved in sea water ( which is 0.04 % potassium by weight ) , and is part of many minerals .   Naturally occurring potassium is composed of three isotopes , of which is radioactive . Traces of are found in all potassium , and it is the most common radioisotope in the human body .   Potassium is chemically very similar to sodium , the previous element in group 1 of the periodic table . They have a similar first ionization energy , which allows for each atom to give up its sole outer electron . That they are different elements that combine with the same anions to make similar salts was suspected in 1702 , and was proven in 1807 using electrolysis .   Most industrial applications of potassium exploit the high solubility in water of potassium compounds , such as potassium soaps . Heavy crop production rapidly depletes the soil of potassium , and this can be remedied with agricultural fertilizers containing potassium , accounting for 95 % of global potassium chemical production .   Potassium ions are necessary for the function of all living cells . The transfer of potassium ions through nerve cell membranes is necessary for normal nerve transmission ; potassium depletion can result in numerous abnormalities , including an abnormal heart rhythm and various electrocardiographic ( ECG ) abnormalities . Fresh fruits and vegetables are good dietary sources of potassium . The body responds to the influx of dietary potassium , which raises serum potassium levels , with a shift of potassium from outside to inside cells and an increase in potassium excretion by the kidneys .

neg: Dangerous goods Dangerous goods or hazardous goods are solids , liquids , or gases that can harm people , other living organisms , property , or the environment . They are often subject to chemical regulations . In the United States , United Kingdom and sometimes in Canada , dangerous goods are more commonly known as hazardous materials ( abbreviated as HAZMAT or hazmat ) . Hazmat teams are personnel specially trained to handle dangerous goods , which include materials that are radioactive , flammable , explosive , corrosive , oxidizing , asphyxiating , biohazardous , toxic , pathogenic , or allergenic . Also included are physical conditions such as compressed gases and liquids or hot materials , including all goods containing such materials or chemicals , or may have other characteristics that render them hazardous in specific circumstances .   In the United States , dangerous goods are often indicated by diamond-shaped signage on the item ( see NFPA 704 ) , its container , or the building where it is stored . The color of each diamond indicates its hazard , e.g. , flammable is indicated with red , because fire and heat are generally of red color , and explosive is indicated with orange , because mixing red ( flammable ) with yellow ( oxidizing agent ) creates orange . A nonflammable or nontoxic gas is indicated with green , because all compressed air vessels are this color in France after World War II , and France was where the diamond system of hazmat identification originated .

neg: Olfactory toxicity in fish The olfactory system is the system related to the sense of smell ( olfaction ) . Many fish activities are dependent on olfaction , such as : mating , discriminating kin , avoiding predators , locating food , contaminant avoidance , imprinting and homing . These activities are referred to as `` olfactory-mediated . '' Impairment of the olfactory system threatens survival and has been used as an ecologically relevant sub-lethal toxicological endpoint for fish within studies . Olfactory information is received by sensory neurons , like the olfactory nerve , that are in a covered cavity separated from the aquatic environment by mucus . Since they are in almost direct contact with the surrounding environment , these neurons are vulnerable to environmental changes . Fish can detect natural chemical cues in aquatic environments at concentrations as low as parts per billion ( ppb ) or parts per trillion ( ppt ) .   Studies have shown that exposures to metals , pesticides , or surfactants can disrupt fish olfaction , which can impact their survival and reproductive success . Many studies have indicated copper as a source of olfactory toxicity in fishes , among other common substances . Olfactory toxicity can occur by multiple , complex Modes of Toxic Action .

neg: Silver Silver is the metallic element with the atomic number 47 . Its symbol is Ag , from the Latin argentum , derived from the Greek ὰργὀς ( literally `` shiny '' or `` white '' ) , and ultimately from a Proto-Indo-European language root reconstructed as * h2erǵ - , `` grey '' or `` shining '' . A soft , white , lustrous transition metal , it exhibits the highest electrical conductivity , thermal conductivity , and reflectivity of any metal . The metal is found in the Earth 's crust in the pure , free elemental form ( `` native silver '' ) , as an alloy with gold and other metals , and in minerals such as argentite and chlorargyrite . Most silver is produced as a byproduct of copper , gold , lead , and zinc refining .   Silver has long been valued as a precious metal . Silver metal is used in many bullion coins , sometimes alongside gold : while it is more abundant than gold , it is much less abundant as a native metal . Its purity is typically measured on a per-mille basis ; a 94 % - pure alloy is described as `` 0.940 fine '' . As one of the seven metals of antiquity , silver has had an enduring role in most human cultures .   Silver is used in numerous applications other than currency , such as solar panels , water filtration , jewellery , ornaments , high-value tableware and utensils ( hence the term silverware ) , and as an investment medium ( coins and bullion ) . Silver is used industrially in electrical contacts and conductors , in specialized mirrors , window coatings , and in catalysis of chemical reactions . Silver compounds are used in photographic film and X-rays . Dilute silver nitrate solutions and other silver compounds are used as disinfectants and microbiocides ( oligodynamic effect ) , added to bandages and wound-dressings , catheters , and other medical instruments .

neg: Red Gold (potato) Red Gold potato is an early variety of North American potato . It has a red skin with yellow flesh inside . It is resistant to potato leafroll virus and potato virus Y and moderately resistant to common scab , but is susceptible to potato virus a and potato virus s.   ` Red Gold ' was bred in Canada in the 1970s and registered in 1987 .   ` Red Gold ' has a mid season maturity , is medium sized with ovate primary and terminal leaflets . The flowers of this variety have golden yellow anthers and medium berry production . The ` Red Gold ' tubers are round to oval with medium eye depth and the sprouts are very pubescent with a pinkish-yellow apex .

neg: Gold Strike (drink) Gold Strike is a cinnamon liqueur containing gold snippets , produced by Lucas Bols . The company suggests it should be drunk as a shot , with the motto `` Shake , Shoot and Strike '' . It 's a clear liquid that tastes like cinnamon candy .   Though the company website states the gold flakes are `` 24-carat '' , some bottles indicate that the gold has various other levels of purity , such as 22 K or 23.5 K . The gold flakes present little health risk . A common urban legend about Gold Strike is that the gold flakes cut the throat or stomach upon ingestion , allowing the alcohol to directly enter the bloodstream for quicker intoxication .   Other alcoholic beverages that contain gold are Goldschläger and Goldwasser .   It is one of many cinnamon-infused liquors on the market . See Fireball and discussion therein .

neg: 2015 Gold King Mine waste water spill The 2015 Gold King Mine waste water spill was an environmental disaster that began at the Gold King Mine near Silverton , Colorado , when EPA personnel , along with workers for Environmental Restoration LLC ( a Missouri company under EPA contract to mitigate pollutants from the closed mine ) , caused the release of toxic waste water into the Animas River watershed . They caused the accident while attempting to drain ponded water near the entrance of the mine on August 5 . The maintenance by the EPA was necessary because local jurisdictions had previously refused Superfund money to fully remediate the regions ' derelict mines , due to a fear of lost tourism . After the spill , the Silverton Board of Trustees and the San Juan County Commission approved a joint resolution seeking Superfund money .   Contractors accidentally destroyed the plug holding water trapped inside the mine , which caused an overflow of the pond , spilling 3 MUSgal of mine waste water and tailings , including heavy metals such as cadmium and lead , and other toxic elements , such as arsenic , beryllium , zinc , iron and copper into Cement Creek , a tributary of the Animas River in Colorado . The EPA was criticized for not warning Colorado and New Mexico about the operation until the day after the waste water spilled , despite the fact the EPA employee `` in charge of Gold King Mine knew of blowout risk . ''   The EPA has taken responsibility for the incident , but refused to pay for any damages claims filed after the accident on grounds of sovereign immunity , pending special authorization from Congress or re-filing of lawsuits in federal court . Governor of Colorado John Hickenlooper declared the affected area a disaster zone . The spill affects waterways of municipalities in the states of Colorado , New Mexico , and Utah , as well as the Navajo Nation . As of August 11 , acidic water continued to spill at a rate of 500 -- while remediation efforts were underway .

neg: Carbon Carbon ( from carbo `` coal '' ) is a chemical element with symbol C and atomic number 6 . It is nonmetallic and tetravalent -- making four electrons available to form covalent chemical bonds . Three isotopes occur naturally , C and C being stable , while C is a radioactive isotope , decaying with a half-life of about 5,730 years . Carbon is one of the few elements known since antiquity .   Carbon is the 15th most abundant element in the Earth 's crust , and the fourth most abundant element in the universe by mass after hydrogen , helium , and oxygen . Carbon 's abundance , its unique diversity of organic compounds , and its unusual ability to form polymers at the temperatures commonly encountered on Earth enables this element to serve as a common element of all known life . It is the second most abundant element in the human body by mass ( about 18.5 % ) after oxygen .   The atoms of carbon can bond together in different ways , termed allotropes of carbon . The best known are graphite , diamond , and amorphous carbon . The physical properties of carbon vary widely with the allotropic form . For example , graphite is opaque and black while diamond is highly transparent . Graphite is soft enough to form a streak on paper ( hence its name , from the Greek verb '' γράφειν '' which means `` to write '' ) , while diamond is the hardest naturally occurring material known . Graphite is a good electrical conductor while diamond has a low electrical conductivity . Under normal conditions , diamond , carbon nanotubes , and graphene have the highest thermal conductivities of all known materials . All carbon allotropes are solids under normal conditions , with graphite being the most thermodynamically stable form . They are chemically resistant and require high temperature to react even with oxygen .   The most common oxidation state of carbon in inorganic compounds is +4 , while +2 is found in carbon monoxide and transition metal carbonyl complexes . The largest sources of inorganic carbon are limestones , dolomites and carbon dioxide , but significant quantities occur in organic deposits of coal , peat , oil , and methane clathrates . Carbon forms a vast number of compounds , more than any other element , with almost ten million compounds described to date , and yet that number is but a fraction of the number of theoretically possible compounds under standard conditions . For this reason , carbon has often been referred to as the `` king of the elements '' .

neg: Five guineas (British coin) The British Five Guinea coin was a machine-struck currency produced from 1668 -- 1753 . It was a gold coin 37 millimetres in diameter and weighing between 41 and 42 grams . Although the coin is now known as the `` five guinea '' piece , during the 17th and 18th centuries it was also known as a five-pound piece , as during the reign of Charles II a guinea was worth twenty shillings -- until its value was fixed at twenty-one shillings by a Royal Proclamation in 1717 the value fluctuated rather in the way that bullion coins do today .   This denomination shows the year of striking on the reverse ; but also the edge inscription -- An ornament and a safeguard , in the year of the reign ... -- is followed by the regnal year of the monarch , in Latin words . In the case of Charles II , the regnal year is calculated from the execution of Charles I , so 1668 is , the twentieth year of the reign . The edge inscription was put on the coin before the other two sides were struck -- in the early years the blanks were cut out from a strip of gold which had been produced by horse power , then the blanks were sent to have the edge inscriptions impressed by a secret process devised by one Pierre Blondeau , a former engineer from the Paris mint who jealously guarded his methods . The blanks were then returned to the mint to have the obverse and reverse struck in a hand-operated press . Samuel Pepys gives a long and detailed description of the rolling , cutting , and striking of the blanks in his diary entry for 19 May 1663 .   Many of the coins produced up to 1699 have an elephant and castle beneath the monarch 's head , indicating that the gold was provided by the Africa Company . Coins of 1703 ( Queen Anne ) have the word VIGO under the Queen 's head , indicating that the gold was captured from Spanish galleons in the Battle of Vigo Bay in October 1702 , but very few of these coins now remain in existence and they are extremely valuable ( up to # 50,000 ) .

neg: Metal ions in aqueous solution A metal ion in aqueous solution ( aqua ion ) is a cation , dissolved in water , of chemical formula -LSB- M ( H2O ) n -RSB- z + . The solvation number , n , determined by a variety of experimental methods is 4 for Li + and Be2 + and 6 for elements in periods 3 and 4 of the periodic table . Lanthanide and actinide aqua ions have solvation number of 8 and 9 . The strength of the bonds between the metal ion and water molecules in the primary solvation shell increases with the electrical charge , z , on the metal ion and decreases as its radius , r , increases . Aqua ions are subject to hydrolysis . The logarithm of the first hydrolysis constant is proportional to z2/r for most aqua ions . The aqua ion is associated , through hydrogen bonding with other water molecules in a secondary solvation shell . Water molecules in the first hydration shell exchange with molecules in the second solvation shell and molecules in the bulk liquid . The residence time of a molecule in the first shell varies among the chemical elements from about 100 picoseconds to more than 200 years . Aqua ions are prominent in electrochemistry .

neg: Base (chemistry) In chemistry , bases are substances that , in aqueous solution , are slippery to the touch , taste astringent , change the color of indicators ( e.g. , turn red litmus paper blue ) , react with acids to form salts , promote certain chemical reactions ( base catalysis ) , accept protons from any proton donor , and/or contain completely or partially displaceable OH − ions . Examples of bases are the hydroxides of the alkali metals and alkaline earth metals ( NaOH , Ca ( OH ) 2 , etc. ) .   These particular substances produce hydroxide ions ( OH − ) in aqueous solutions , and are thus classified as Arrhenius bases .  For a substance to be classified as an Arrhenius base , it must produce hydroxide ions in an aqueous solution . In order to do so , Arrhenius believed the base must contain hydroxide in the formula . This makes the Arrhenius model limited , as it can not explain the basic properties of aqueous solutions of ammonia ( NH3 ) or its organic derivatives ( amines ) . There are also bases that do not contain a hydroxide ion but nevertheless react with water , resulting in an increase in the concentration of the hydroxide ion . An example of this is the reaction between ammonia and water to produce ammonium and hydroxide . In this reaction ammonia is the base because it accepts a proton from the water molecule . Ammonia and other bases similar to it usually have the ability to form a bond with a proton due to the unshared pair of electrons that they possess . In the more general Brønsted -- Lowry acid -- base theory , a base is a substance that can accept hydrogen cations ( H + ) -- otherwise known as protons . In the Lewis model , a base is an electron pair donor .   In water , by altering the autoionization equilibrium , bases yield solutions in which the hydrogen ion activity is lower than it is in pure water , i.e. , the water has a pH higher than 7.0 at standard conditions . A soluble base is called an alkali if it contains and releases OH − ions quantitatively . However , it is important to realize that basicity is not the same as alkalinity . Metal oxides , hydroxides , and especially alkoxides are basic , and counteranions of weak acids are weak bases .   Bases can be thought of as the chemical opposite of acids . However , some strong acids are able to act as bases . Bases and acids are seen as opposites because the effect of an acid is to increase the hydronium ( H3O + ) concentration in water , whereas bases reduce this concentration . A reaction between an acid and base is called neutralization . In a neutralization reaction , an aqueous solution of a base reacts with an aqueous solution of an acid to produce a solution of water and salt in which the salt separates into its component ions . If the aqueous solution is saturated with a given salt solute , any additional such salt precipitates out of the solution .   The notion of a base as a concept in chemistry was first introduced by the French chemist Guillaume François Rouelle in 1754 . He noted that acids , which at that time were mostly volatile liquids ( like acetic acid ) , turned into solid salts only when combined with specific substances . Rouelle considered that such a substance serves as a `` base '' for the salt , giving the salt a `` concrete or solid form '' .

neg: Crown Estate The Crown Estate is a collection of lands and holdings in the United Kingdom belonging to the British monarch as a corporation sole , making it the `` Sovereign 's public estate '' , which is neither government property nor part of the monarch 's private estate . As a result of this arrangement , the sovereign is not involved with the management or administration of the estate , exercising only very limited control of its affairs . Instead , the estate 's extensive portfolio is overseen by a semi-independent , incorporated public body headed by the Crown Estate Commissioners , who exercise `` the powers of ownership '' of the estate , although they are not `` owners in their own right '' . The revenues from these hereditary possessions have been placed by the monarch at the disposition of Her Majesty 's Government and thus proceed directly to Her Majesty 's Treasury for the benefit of the British nation . The Crown Estate is formally accountable to the Parliament of the United Kingdom , where it is legally mandated to make an annual report to the sovereign , a copy of which is forwarded to the House of Commons .   The Crown Estate is one of the largest property managers in the United Kingdom , overseeing property worth # 12 billion , with urban properties valued at # 9.1 billion representing the majority of the estate by value . These include a large number of properties in central London , but the estate also controls 792000 ha of agricultural land and forest , more than half of the UK 's foreshore , and retains various other traditional holdings and rights , including Ascot Racecourse and Windsor Great Park . Naturally occurring gold and silver in the UK , collectively known as `` Mines Royal '' , are managed by The Crown Estate and leased to mining operators .   Historically , Crown Estate properties were administered by the reigning monarch to help fund the business of governing the country . However , in 1760 , George III surrendered control over the Estate 's revenues to the treasury , thus relieving him of the responsibility of personally paying for the costs of the civil service , defence costs , the national debt , and his own personal debts . In return , he received an annual grant known as the Civil list . By tradition , each subsequent monarch agreed to this arrangement upon his or her accession . However , from 1 April 2012 , under the terms of the Sovereign Grant Act 2011 ( SSG ) , the Civil List was abolished and the monarch was thenceforth provided with a stable source of revenue indexed to a percentage of the Crown Estate 's annual net revenue ( currently set at 15 % ) . This was intended to provide a long-term solution and remove the politically sensitive issue of Parliament having to debate the Civil List allowance every ten years . Subsequently , the Sovereign Grant Act allows for all future monarchs to simply extend these provisions for their reigns by Order in Council . The act does not imply any legal change on the nature of the estate 's ownership , but is simply a benchmark by which the sovereign grant is set as a grant by Parliament .

neg: Tetraxenonogold(II) Tetraxenonogold ( II ) , gold tetraxenide ( II ) or AuXe is a cationic complex with a square planar configuration of atoms . It is found in the compound AuXe ( SbF ) , which exists in triclinic and tetragonal crystal modifications . The AuXe ion is stabilised by interactions with the fluoride atoms of the counterion . The Au-Xe bond length is 274 pm .   Tetraxenonogold ( II ) is unusual in that it is a compound of the notoriously inert atoms xenon and gold . It is also unusual in that it uses xenon as a transition metal ligand , and in that it contains gold in the +2 oxidation state . It can be produced by reduction of AuF3 in the presence of fluoroantimonic acid and xenon , and crystallised at low temperature . The xenon bonds with the gold ( II ) ion to make this complex .

neg: Fine chemical Fine chemicals are complex , single , pure chemical substances , produced in limited quantities in multipurpose plants by multistep batch chemical or biotechnological processes . They are described by exacting specifications , used for further processing within the chemical industry and sold for more than $ 10/kg ( see the comparison of fine chemicals , commodities and specialties ) . The class of fine chemicals is subdivided either on the basis of the added value ( building blocks , advanced intermediates or active ingredients ) , or the type of business transaction , namely standard or exclusive products .   Fine chemicals are produced in limited volumes ( < 1000 tons/year ) and at relatively high prices ( > $ 10/kg ) according to exacting specifications , mainly by traditional organic synthesis in multipurpose chemical plants . Biotechnical processes are gaining ground . The global production value is about $ 85 billion . Fine chemicals are used as starting materials for specialty chemicals , particularly pharmaceuticals , biopharmaceuticals and agrochemicals . Custom manufacturing for the life science industry plays a big role ; however , a significant portion of the fine chemicals total production volume is manufactured in house by large users . The industry is fragmented and extends from small , privately owned companies to divisions of big , diversified chemical enterprises . The term `` fine chemicals '' is used in distinction to `` heavy chemicals '' , which are produced and handled in large lots and are often in a crude state .   Since their inception in the late 1970s , fine chemicals have become an important part of the chemical industry . The total production value of $ 85 billion is split about 60 / 40 among in-house production by the main consumers , the life science industry , on the one hand , and the fine chemicals industry on the other hand . The latter pursues both a `` supply push '' strategy , whereby standard products are developed in-house and offered ubiquitously , and a `` demand pull '' strategy , whereby products or services determined by the customer are provided exclusively on a `` one customer / one supplier '' basis . The products are mainly used as building blocks for proprietary products . The hardware of the top tier fine chemical companies has become almost identical . The design , lay-out and equipment of the plants and laboratories has become practically the same all over the world . Most chemical reactions performed go back to the days of the dyestuff industry . Numerous regulations determine the way labs and plants have to be operated , thereby contributing to the uniformity .

neg: Sulfur Sulfur or sulphur ( see spelling and etymology ) is a chemical element with symbol S and atomic number 16 . It is abundant , multivalent , and nonmetallic . Under normal conditions , sulfur atoms form cyclic octatomic molecules with a chemical formula S8 . Elemental sulfur is a bright yellow crystalline solid at room temperature . Chemically , sulfur reacts with all elements except for gold , platinum , iridium , tellurium , and the noble gases .   Though sometimes found in pure , native form , sulfur usually occurs as sulfide and sulfate minerals . Being abundant in native form , sulfur was known in ancient times , being mentioned for its uses in ancient India , ancient Greece , China , and Egypt . In the Bible , sulfur is called brimstone . Today , almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum . The greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers , and other chemical processes . The element sulfur is used in matches , insecticides , and fungicides . Many sulfur compounds are odoriferous , and the smells of odorized natural gas , skunk scent , grapefruit , and garlic are due to organosulfur compounds . Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes .   Sulfur is an essential element for all life , but almost always in the form of organosulfur compounds or metal sulfides . Three amino acids ( cysteine , cystine , and methionine ) and two vitamins ( biotin and thiamine ) are organosulfur compounds . Many cofactors also contain sulfur including glutathione and thioredoxin and iron -- sulfur proteins . Disulfides , S -- S bonds , confer mechanical strength and insolubility of the protein keratin , found in outer skin , hair , and feathers . Sulfur is one of the core chemical elements needed for biochemical functioning and is an elemental macronutrient for all organisms .

neg: Arsenopyrite Arsenopyrite is an iron arsenic sulfide ( FeAsS ) . It is a hard ( Mohs 5.5-6 ) metallic , opaque , steel grey to silver white mineral with a relatively high specific gravity of 6.1 . When dissolved in nitric acid , it releases elemental sulfur . When arsenopyrite is heated , it becomes magnetic and gives off toxic fumes . With 46 % arsenic content , arsenopyrite , along with orpiment , is a principal ore of arsenic . When deposits of arsenopyrite become exposed to the atmosphere , usually due to mining , the mineral will slowly oxidize , converting the arsenic into oxides that are more soluble in water , leading to acid mine drainage .   The crystal habit , hardness , density , and garlic odor when struck are diagnostic . Arsenopyrite in older literature may be referred to as mispickel , a name of German origin .   Arsenopyrite also can be associated with significant amounts of gold . Consequently , it serves as an indicator of gold bearing reefs . Many arsenopyrite gold ores are refractory , i.e. the gold is not easily cyanide leached from the mineral matrix .   Arsenopyrite is found in high temperature hydrothermal veins , in pegmatites , and in areas of contact metamorphism or metasomatism .

neg: Waterproof fabric Waterproof fabrics are fabrics that are inherently , or have been treated to become , resistant to penetration by water and wetting . The term `` waterproof '' refers to conformance to a governing specification and specific conditions of a laboratory test method . They are usually natural or synthetic fabrics that are laminated to or coated with a waterproofing material such as rubber , polyvinyl chloride ( PVC ) , polyurethane ( PU ) , silicone elastomer , fluoropolymers , and wax . Treatment could be either of the fabric during manufacture or of completed products after manufacture , for instance by a waterproofing spray . Examples include the rubberised fabric used in Mackintosh jackets , sauna suits and inflatable boats . They are even used for footballs and glasses .   The most common waterproofing treatment in the early 2000s was the application of C8 fluorocarbon-based textile finishes during manufacture . However , environmental and health concerns led to a transition to C6 fluorocarbon-based finishes and the development of alternative chemistries , such as ChemStik technology , a solvent-free process involving the on-surface polymerization of hydrocarbon chains .

neg: Rhodamine 6G Rhodamine 6G -LSB- ˈroʊdəmiːn -RSB- is a highly fluorescent rhodamine family dye . It is often used as a tracer dye within water to determine the rate and direction of flow and transport . Rhodamine dyes fluoresce and can thus be detected easily and inexpensively with instruments called fluorometers . Rhodamine dyes are used extensively in biotechnology applications such as fluorescence microscopy , flow cytometry , fluorescence correlation spectroscopy and ELISA .     Rhodamine 6G is also used as a laser dye , or gain medium , in dye lasers , and is pumped by the 2nd ( 532 nm ) harmonic from an Nd : YAG laser or nitrogen laser . The dye has a remarkably high photostability , high fluorescence quantum yield ( 0.95 ) , low cost , and its lasing range has close proximity to its absorption maximum ( approximately 530 nm ) . The lasing range of the dye is 555 to 585 nm with a maximum at 566 nm .   Rhodamine 6G usually comes in three different forms . Rhodamine 6G chloride is a bronze/red powder with the chemical formula C27H29ClN2O3 . Although highly soluble , this formulation is very corrosive to all metals except stainless steel . Other formulations are less soluble , but also less corrosive . Rhodamine 6G perchlorate ( C27H29ClN2O7 ) comes in the form of red crystals , while rhodamine 6G tetrafluoroborate ( C27H29BF4N2O3 ) appears as maroon crystals .


query: There is a geologic period that spans 43 million years called Paleogene.

pos: Paleogene The Paleogene ( -LSB- pronˈpæliːədʒiːn -RSB- or -LSB- ˈpeɪliːədʒiːn -RSB- also spelled Palaeogene or Palæogene ; informally Lower Tertiary ) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago ( Mya ) to the beginning of the Neogene Period Mya . It is the beginning of the Cenozoic Era of the present Phanerozoic Eon . The Paleogene is most notable for being the time during which mammals diversified from relatively small , simple forms into a large group of diverse animals in the wake of the Cretaceous -- Paleogene extinction event that ended the preceding Cretaceous Period .   This period consists of the Paleocene , Eocene and Oligocene epochs . The end of the Paleocene ( 55.5 / 54.8 Mya ) was marked by the Paleocene -- Eocene Thermal Maximum , one of the most significant periods of global change during the Cenozoic , which upset oceanic and atmospheric circulation and led to the extinction of numerous deep-sea benthic foraminifera and on land , a major turnover in mammals . The terms ` Paleogene System ' ( formal ) and ` lower Tertiary System ' ( informal ) are applied to the rocks deposited during the ` Paleogene Period ' . The somewhat confusing terminology seems to be due to attempts to deal with the comparatively fine subdivisions of time possible in the relatively recent geologic past , for which more details are preserved . By dividing the Tertiary Period into two periods instead of directly into five epochs , the periods are more closely comparable to the duration of ` periods ' of the preceding Mesozoic and Paleozoic Eras .

neg: Evolution of reptiles Reptiles arose about 310 -- 320 million years ago during the Carboniferous period . Reptiles , in the traditional sense of the term , are defined as animals that have scales or scutes , lay land-based hard-shelled eggs , and possess ectothermic metabolisms . So defined , the group is paraphyletic , excluding endothermic animals like birds and mammals that are descended from early reptiles . A definition in accordance with phylogenetic nomenclature , which rejects paraphyletic groups , includes birds while excluding mammals and their synapsid ancestors . So defined , Reptilia is identical to Sauropsida .   Though few reptiles today are apex predators , many examples of apex reptiles have existed in the past . Reptiles have an extremely diverse evolutionary history that has led to biological successes , such as dinosaurs , pterosaurs , plesiosaurs , mosasaurs , and ichthyosaurs .

neg: Sternberg Formation The Sternberg Formation is a geologic formation in Germany . It preserves fossils dating back to the Paleogene period .

neg: Radiometric dating Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon , in which trace radioactive impurities were selectively incorporated when they were formed . The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products , which form at a known constant rate of decay . The use of radiometric dating was first published in 1907 by Bertram Boltwood and is now the principal source of information about the absolute age of rocks and other geological features , including the age of fossilized life forms or the age of the Earth itself , and can also be used to date a wide range of natural and man-made materials .   Together with stratigraphic principles , radiometric dating methods are used in geochronology to establish the geological time scale . Among the best-known techniques are radiocarbon dating , potassium-argon dating and uranium-lead dating . By allowing the establishment of geological timescales , it provides a significant source of information about the ages of fossils and the deduced rates of evolutionary change . Radiometric dating is also used to date archaeological materials , including ancient artifacts .   Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied .

neg: Arikareean The Arikareean North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology ( NALMA ) , typically set from 30,600,000 to 20,800,000 years BP , a period of . It is usually considered to overlap the Oligocene and Miocene epochs . The Arikareean is preceded by the Whitneyan and followed by the Hemingfordian NALMA stages .   The Arikareean can be further divided into the substages of :  late Late Arikareean : Lower boundary source , base of Geringian ( approximate )  early Late Arikareean : base of Geringian ( approximate ) . Upper boundary source : base of Hemingfordian ( approximate ) .  late Early Arikareean : Lower boundary source of base of Geringian ( approximate ) . Upper boundary source of base of Hemingfordian ( approximate ) .  early Early Arikareean ( shares lower boundary ) : Upper boundary source of base of Hemingfordian ( approximate ) .

neg: Geological formation A formation or geological formation is the fundamental unit of lithostratigraphy . A formation consists of a certain number of rock strata that have a comparable lithology , facies or other similar properties . Formations are not defined on the thickness of the rock strata they consist of and the thickness of different formations can therefore vary widely .   The concept of formally defined layers or strata is central to the geologic discipline of stratigraphy . Formations can be divided into members and are themselves frequently parcelled together in groups .

neg: Ordovician–Silurian extinction events The Ordovician -- Silurian extinction events , when combined , are the second-largest of the five major extinction events in Earth 's history in terms of percentage of genera that became extinct . This event greatly affected marine communities , which caused the disappearance of one third of all brachiopod and bryozoan families , as well as numerous groups of conodonts , trilobites , and graptolites . The Ordovician-Silurian extinction occurred during the Hirnantian stage of the Ordovician Period and the subsequent Rhuddanian stage of the Silurian Period . The last event is dated in the interval of 455 -- 430 Ma ago , i.e. , lasting from the Middle Ordovician to Early Silurian , thus including the extinction period . This event was the first of the big five Phanerozoic events and was the first to significantly affect animal-based communities .   Almost all major taxonomic groups were affected during this extinction event . Extinction was global during this period , eliminating 49-60 % of marine genera and nearly 85 % of marine species .   Brachiopods , bivalves , echinoderms , bryozoans and corals were particularly affected . Prior to the late Ordovician cooling , temperatures were relatively warm and it is the suddenness of the climate changes and the elimination of habitats due to sea-level fall that are believed to have precipitated the extinctions . The falling sea level disrupted or eliminated habitats along the continental shelves . Evidence for the glaciation was found through deposits in the Sahara Desert . A combination of lowering of sea level and glacially driven cooling were likely driving agents for the Ordovician mass extinction .

neg: Hordaland Formation The Hordaland Formation is a geologic formation in Norway . It preserves fossils dating back to the Paleogene period .

neg: Paleopathology Paleopathology , also spelled palaeopathology , is the study of ancient diseases . Studying pathologies , these abnormalities in biologic individuals and systems , may be intrinsic to the system itself ( examples : autoimmune disorders or traumatic arthritis ) or caused by an extrinsic factor ( examples : viruses or lead poisoning from pipes ) . Any living organism can have a pathology . Studies have historically focused on humans , but there is no evidence that humans are more prone to pathologies than any other animal .   Paleopathology is an interdisciplinary science . The majority of the work has historically been done by anthropologists studying diseases in ancient cultures . Medically trained professionals have also made substantial contributions , especially in modern comparative studies . Paleontologists have sporadically contributed to the field , focusing on non-avian dinosaurs and Cenozoic mammals .

neg: Coal forest Coal forests were the vast swathes of wetlands that covered much of the Earth 's tropical land areas during the late Carboniferous ( Pennsylvanian ) and Permian times . As vegetable matter from these forests decayed , enormous deposits of peat accumulated , which later changed into coal .   Much of the carbon in the peat deposits produced by coal forests came from photosynthetic splitting of existing carbon dioxide , which released the accompanying split-off oxygen into the atmosphere . This process may have greatly increased the oxygen level , possibly as high as about 35 % , making the air more easily breathable by animals with inefficient respiratory systems , as indicated by the size of Meganeura compared to modern dragonflies .   Coal forests covered tropical Euramerica ( Europe , eastern North America , northwesternmost Africa ) and Cathaysia ( mainly China ) . Climate change devastated these tropical rainforests during the Carboniferous period . The Carboniferous Rainforest Collapse was caused by a cooler drier climate that initially fragmented , then collapsed the rainforest ecosystem . During most of the rest of Carboniferous times , the coal forests were mainly restricted to refugia in North America ( such as the Appalachian and Illinois coal basins ) and central Europe .   At the very end of the Carboniferous period , the coal forests underwent a resurgence , expanding mainly in eastern Asia , notably China ; they never recovered fully in Euramerica . The Chinese coal forests continued to flourish well into Permian times . This resurgence of the coal forests in very late Carboniferous times seems to have coincided with a lowering of global temperatures and a return of extensive polar ice in southern Gondwana , perhaps due to lessening of the greenhouse effect as the massive coal deposition process abstracted carbon dioxide from the atmosphere .

neg: Geology of South Wales South Wales is an area with many features of outstanding interest to geologists , who have for long used the area for University field trips .   This varied and accessible region has provided a written record of geological interest that dates to the 12th century , when Giraldus Cambrensis noted pyritous shales near Newport . Some of the first published representations of fossils were of fossil plants from coal measures near Neath ( Gibson late 17th century ) . The British geologists Adam Sedgwick and Roderick Murchison did fundamentally important work in South Wales on Old Red Sandstone and the underlying rocks . The first volume of memoirs ( 1846 ) published by the Geological Survey contained a conspectus of the geology of South Wales that set a template for all future work .   Significant discoveries continue to be made . For instance , in Carmarthenshire , in the late 70s , John Cope detected a small area of Precambrian and Cambrian rocks . Other parts of South Wales , however , have not seen a Geological Survey officer since the mid-19th century . The geology of south Wales was central to the massive contribution Wales made to the Industrial Revolution .   Several successive periods are represented , including all of the Palaeozoic periods . Pembrokeshire has outcrops of both Precambrian and Cambrian ( 542-488 million years ago ) rocks . A notable feature of the Ordovician system ( 488-444 million years old ) is a major subsidence area , or basin , which later filled with substantial thicknesses of mostly sandy and muddy sediment . The line of the shallower continental shelf area , to the south-east , ran approximately from the Long Mynd ( in Shropshire ) to Haverfordwest in Pembrokeshire . Some volcanic action also occurred . This thick sedimentary deposition continued into the Silurian period ( 444-416 million years old ) . Silurian volcanicity led to production of lavas at localised sites such as Skomer Island .   Silurian rocks are widely distributed in south Wales and are well displayed on the Cardiganshire coast . The Silurian and earlier rocks were folded , faulted , and distorted several times , notably during the late Ordovician , and late Silurian , by which time the area had begun to rise above sea level as mountain ranges were uplifted to the north-west . This was caused by the collision of a proto-North America ( `` Laurentia '' ) and the present southern Britain ( `` Eastern Avalonia '' ) . The intervening sea , the Iapetus Ocean , closed as a result of plate tectonic movements , similar to those that now close the Mediterranean Sea between Europe and Africa .   The succeeding Devonian period ( 416-359 million years ago ) saw mostly alluvial deposits ( `` Old Red Sandstone '' ) , which were interrupted by major uplift . Following this , the land subsided again in the Carboniferous period ( 359-299 million years ago ) . In the early Carboniferous period , limestones were deposited on a continental shelf , which deepened towards the south where there was a major sea area . During earth movements caused by the approach of a continent from the south , sea shallowing led to thick alluvial and coastal plain sediments ( see below ) containing economic developments of coal . Carboniferous Limestone outcrops occur in south Pembrokeshire , the Gower Peninsula , the Vale of Glamorgan and around the edge of the coalfield .   At the end of the Carboniferous , during Permian ( 299-251 my ago ) time , Wales is thought to have been a landmass . Only in late Triassic ( 251-200 my ago ) times did deposition return , with coarse-grained screes forming around a series of low but rugged hills . Continuing deposition led to the formation of the early Jurassic deposits of mudstones and muddy limestones ( the `` Lias '' ) . Deposits later than this are almost completely absent , although the Chalk sea probably covered most of Wales between 100 and 66 million years ago . Any such later deposits have been eroded away .   One of the geological rarities of south Wales is the coastline of St Brides Major at Ogmore-by-Sea and Southerndown . Its cliffs are composed partly of earliest Jurassic Sutton stone , a rare freestone that is a marginal or coastal deposit derived in part from erosion of carboniferous limestone . Sutton stone has always been highly regarded : as well as being used in construction throughout the Vale of Glamorgan , it was also shipped over the Bristol Channel to North Devon and North Cornwall , which are both deficient in limestone .   A major geological feature of the Upper Carboniferous rocks in south Wales is the south Wales coalfield . The rocks comprising this important area were laid down during the later Carboniferous . This sedimentary succession includes a sequence with a thickness of more than 1800 m in the west . The coal measures were laid down on a low-lying waterlogged plain with peat mires immediately south of an ancient and persistent geological feature known as the Wales-London-Brabant High . Burial converted the peat deposits to thinner coal seams . Later earth movements distorted the coal-bearing strata , and the difficulty of mining led to premature closure of many mines on economic grounds , especially in Pembrokeshire where seams were squeezed completely out of shape .

neg: Illinoian (stage) The Illinoian Stage is the name used by Quaternary geologists in North America to designate the period c. 191,000 to c. 130,000 years ago , during the middle Pleistocene , when sediments comprising the Illinoian Glacial Lobe were deposited . It precedes the Sangamonian stage and follows the Pre-Illinoian Stage in North America . The Illinoian Stage is defined as the period of geologic time during which the glacial tills and outwash , which comprise the bulk of the Glasford Formation , accumulated to create the Illinoian Glacial Lobe .

neg: Proterozoic The Proterozoic ( -LSB- pronˌproʊtərəˈzoʊɪk , _ prɔː - , _ - trə - -RSB- ) is a geological eon representing the time just before the proliferation of complex life on Earth . The name Proterozoic comes from Greek and means `` earlier life '' , the Greek root protero - , means `` former , earlier '' and zoic - , means `` animal , living being '' . The Proterozoic Eon extended from to ( million years ago ) , and is the most recent part of the Precambrian Supereon . It is subdivided into three geologic eras ( from oldest to youngest ) : the Paleoproterozoic , Mesoproterozoic , and Neoproterozoic .   The well-identified events of this eon were the transition to an oxygenated atmosphere during the Paleoproterozoic ; several glaciations , which produced the hypothesized Snowball Earth during the Cryogenian Period in the late Neoproterozoic Era ; and the Ediacaran Period ( 635 to 541 Ma ) which is characterized by the evolution of abundant soft-bodied multicellular organisms and provides us with the first obvious fossil evidence of life on earth .

neg: Midway Formation The Midway Formation is a geologic formation in Texas . It preserves fossils dating back to the Paleogene period .

neg: Chronology of the universe The chronology of the universe describes the history and future of the universe according to Big Bang cosmology .  The metric expansion of space is estimated to have begun 13.8 billion years ago .  For the purposes of this summary , it is convenient to divide the chronology of the universe into four parts :   The very early universe , from the Planck epoch until the cosmic inflation , or the first picosecond of cosmic time ; this period is the domain of active theoretical research , currently beyond the grasp of most experiments in particle physics .  The early universe , from the Quark epoch to the Photon epoch , or the first 380,000 years of cosmic time , when the familiar forces and elementary particles have emerged but the universe remains in the state of a plasma , followed by the `` Dark Ages '' , from 380,000 years to about 150 million years during which the universe was transparent but no large-scale structures had yet formed .  The period of large-scale structure formation , including stellar evolution , galaxy formation and evolution and the formation of galaxy clusters and superclusters , from about 150 million years to present , and prospectively until about 100 billion years of cosmic time ; The thin disk of our galaxy began to form at about 5 billion years . The solar system formed at about 4.6 billion years ago , with the earliest traces of life on Earth emerging by about 3.5 billion years ago .  The far future , after cessation of stellar formation , with various scenarios for the ultimate fate of the universe .

neg: List of European dinosaurs Dinosaurs evolved partway through the Triassic period of the Mesozoic era , around 230 Ma ( million years ago ) . At that time , the earth had one supercontinental landmass , called Pangaea , of which Europe was a part . So it remained throughout the Triassic . By the start of the Jurassic period , some 30 million years later , the supercontinent began to split into Laurasia and Gondwana . The largest inlet from Panthalassa , the superocean that surrounded Pangaea , was called the Tethys Ocean , and as this inlet cut deeper into the supercontinent , much of Europe was flooded .   By the Cretaceous , from 145 to 66 million years ago , the continents were beginning to approach their present shapes , but not their present positions , and Europe remained tropical . At times , it was a chain of island-microcontinents including Baltica and Iberia .   Europe is relatively rich in fossils from the Jurassic-Cretaceous boundary , and much of what is known about European dinosaurs dates from this time . As the timeline below illustrates , there are substantial gaps in our knowledge from the rest of the Mesozoic . The absence of dinosaur genera from this time is because few fossils have been discovered , and almost certainly not because Europe contained few types of dinosaur -- except , perhaps , immediately after the Triassic -- Jurassic extinction event .

neg: Pamunkey Group The Pamunkey Group is a geologic group in Virginia . It preserves fossils dating back to the Paleogene period .

neg: Age (geology) A geologic age is a subdivision of geologic time that divides an epoch into smaller parts . A succession of rock strata laid down in a single age on the geologic timescale is a stage .

neg: Cernay Formation The Cernay Formation is a geologic formation in France . It preserves fossils dating back to the Paleogene period .

neg: Group (stratigraphy) A group in stratigraphy is a lithostratigraphic unit , a part of the geologic record or rock column that consists of defined rock strata . Groups are generally divided into individual formations . Groups may sometimes be divided into `` subgroups '' and are themselves sometimes grouped into `` supergroups '' .   Some well known groups of northwestern Europe have in the past also been used as units for chronostratigraphy and geochronology . These are the Rotliegend , Zechstein ( both of Permian age ) , Buntsandstein , Muschelkalk , Keuper ( Triassic in age ) , Lias , Dogger and Malm ( Jurassic in age ) groups . Because of the confusion this causes , the official geologic timescale of the ICS does not contain any of these names any longer .

neg: Seguin Formation The Seguin Formation is a geologic formation in Texas . It preserves fossils dating back to the Paleogene period .