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The mineral pyrite, or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS2. This mineral's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of ''fool's gold''. The color has also led to the nicknames ''brass'', ''brazzle'', and ''Brazil'', primarily used to refer to pyrite found in coal.〔Julia A. Jackson, James Mehl and Klaus Neuendorf, ( Glossary of Geology ), American Geological Institute (2005) p. 82.〕〔Albert H. Fay, (A Glossary of the Mining and Mineral Industry ), United States Bureau of Mines (1920) pp. 103–104.〕 Pyrite is the most common of the sulfide minerals. The name pyrite is derived from the Greek πυρίτης (''pyritēs''), "of fire" or "in fire",〔(πυρίτης ), Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus〕 in turn from πύρ (''pyr''), "fire".〔(πύρ ), Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus〕 In ancient Roman times, this name was applied to several types of stone that would create sparks when struck against steel; Pliny the Elder described one of them as being brassy, almost certainly a reference to what we now call pyrite.〔James Dwight Dana, Edward Salisbury Dana, (Descriptive Mineralogy, 6th Ed. ), Wiley, New York (1911) p. 86.〕 By Georgius Agricola's time, c. 1550, the term had become a generic term for all of the sulfide minerals.〔Herbert Clark Hoover and Lou Henry Hoover, translators of Georgius Agricola, (Re Metallica ), The Mining Magazine, London (1912; Dover reprint, 1950); see footnote, p. 112.〕 Pyrite is usually found associated with other sulfides or oxides in quartz veins, sedimentary rock, and metamorphic rock, as well as in coal beds and as a replacement mineral in fossils. Despite being nicknamed fool's gold, pyrite is sometimes found in association with small quantities of gold. Gold and arsenic occur as a coupled substitution in the pyrite structure. In the Carlin–type gold deposits, arsenian pyrite contains up to 0.37 wt% gold.〔M. E. Fleet and A. Hamid Mumin, (Gold-bearing arsenian pyrite and marcasite and arsenopyrite from Carlin Trend gold deposits and laboratory synthesis ), American Mineralogist 82 (1997) pp. 182–193〕 ==Uses== Pyrite enjoyed brief popularity in the 16th and 17th centuries as a source of ignition in early firearms, most notably the wheellock, where the cock held a lump of pyrite against a circular file to strike the sparks needed to fire the gun. Pyrite has been used since classical times to manufacture ''copperas'', that is, iron(II) sulfate. Iron pyrite was heaped up and allowed to weather (an example of an early form of heap leaching). The acidic runoff from the heap was then boiled with iron to produce iron sulfate. In the 15th century, such leaching began to replace the burning of sulfur as a source of sulfuric acid. By the 19th century, it had become the dominant method. Pyrite remains in commercial use for the production of sulfur dioxide, for use in such applications as the paper industry, and in the manufacture of sulfuric acid. Thermal decomposition of pyrite into FeS (iron(II) sulfide) and elemental sulfur starts at ; at around pS2 is about . A newer commercial use for pyrite is as the cathode material in Energizer brand non-rechargeable lithium batteries.〔Energizer Corporation, (Lithium Iron Disulfide )〕 Pyrite is a semiconductor material with a band gap of 0.95 eV. During the early years of the 20th century, pyrite was used as a mineral detector in radio receivers, and is still used by 'crystal radio' hobbyists. Until the vacuum tube matured, the crystal detector was the most sensitive and dependable detector available – with considerable variation between mineral types and even individual samples within a particular type of mineral. Pyrite detectors occupied a midway point between galena detectors and the more mechanically complicated perikon mineral pairs. Pyrite detectors can be as sensitive as a modern 1N34A germanium diode detector.〔(The Principles Underlying Radio Communication, Radio Pamphlet No. 40 ), U.S. Army Signal Corps, Dec. 10 (1918) section 179, pp. 302–305.〕〔Thomas H. Lee, (The Design of Radio Frequency Integrated Circuits, 2nd Ed. ), Cambridge University Press (2004) pp. 4–6.〕 Pyrite has been proposed as an abundant, inexpensive material in low cost photovoltaic solar panels. Synthetic iron sulfide was used with copper sulfide to create the photovoltaic material.〔(Cheaper materials could be key to low-cost solar cells ) by Robert Sanders, 17 February 2009〕 Pyrite is used to make marcasite jewelry. Marcasite jewelry, made from small faceted pieces of pyrite, often set in silver, was known since ancient times and was popular in the Victorian era.〔 〕 At the time when the term became common in jewelry making, "marcasite" referred to all iron sulfides including pyrite, and not to the orthorhombic FeS2 mineral marcasite which is lighter in color, brittle and chemically unstable, and thus not suitable for jewelry making. Marcasite jewelry does not actually contain the mineral marcasite. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pyrite」の詳細全文を読む スポンサード リンク
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