| Pyrite | |
|---|---|
 A mass of intergrown, striated pyrite crystals | |
| General | |
| Category | Sulfide mineral |
| Chemical formula | iron disulfide (FeS2) |
| Identification | |
| Color | Pale brass yellow, dull gold |
| Crystal habit | Cubic, faces may be striated, but also frequently octahedral and pyritohedron. A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 In Chemistry, a disulfide usually refers to the structural unit composed of a linked pair of sulfur atoms In Mineralogy, shape and size give rise to descriptive terms applied to the typical appearance or habit of Crystals The many terms used by mineralogists Often inter-grown, massive, radiated, granular, globular and stalactitic. |
| Crystal system | Isometric; bar 3 2/m |
| Twinning | Penetration twinning |
| Cleavage | Poor |
| Fracture | Very uneven, sometimes conchoidal |
| Mohs Scale hardness | 6–6. A crystal system is a category of Space groups which characterize Symmetry of structures in three dimensions with Translational symmetry in three directions The cubic crystal system (or isometric) is a Crystal system where the Unit cell is in the shape of a Cube. Crystal twinning occurs when two separate crystals share some of the same Crystal lattice points in a symmetrical manner Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types In the field of Mineralogy, fracture is a term used to describe the shape and texture of the surface formed when a Mineral is broken The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material 8 |
| Luster | Metallic, glistening |
| Refractive index | Opaque |
| Streak | Greenish-black to brownish-black; smells of sulfur |
| Specific gravity | 4. Lustre (or luster) is a description of the way light interacts with the surface of a Crystal, rock, or Mineral. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium The streak (also called powder color) of a Mineral is the Color of the powder produced when it is dragged across an unweathered surface Specific gravity is defined as the ratio of the Density of a given solid or liquid substance to the density of water at a specific temperature and pressure typically 95–5. 10 |
| Fusibility | 2. Fusibility is the ease with which a material will Melt. Materials such as solder require a low melting point so that when heat is applied to a joint the solder will melt before 5–3 to a magnetic globule |
| Solubility | insoluble in water |
| Other Characteristics | paramagnetic |
| References | [1][2][3] |
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. Paramagnetism is a form of magnetism which occurs only in the presence of an externally applied magnetic field A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific The term sulfide ( sulphide in British English) refers to several types of Chemical compounds containing Sulfur in its lowest Oxidation A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold due to its resemblance to gold. Lustre (or luster) is a description of the way light interacts with the surface of a Crystal, rock, or Mineral. Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Pyrite is the most common of the sulfide minerals. A sulfide mineral is a Mineral containing Sulfide (S2- as the major Anion. The name pyrite is derived from the Greek πυρίτης (puritēs), “of fire” or "in fire”, from πύρ (pur), “fire”. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly This name is likely due to the sparks that result when pyrite is struck against steel or flint. Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 Flint (or flintstone) is a hard sedimentary Cryptocrystalline form of the Mineral Quartz, categorized as a variety of Chert This property made pyrite popular for use in early firearms such as the wheellock. A firearm is a Tool that projects either single or multiple Projectiles at high velocity through a controlled explosion Wheellock, wheel-lock or wheel lock, is a mechanism for firing a Firearm.
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Mineralogy
This mineral occurs as isometric crystals that usually appear as cubes. The cubic crystal system (or isometric) is a Crystal system where the Unit cell is in the shape of a Cube. In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating The cube faces may be striated (parallel lines on crystal surface or cleavage face) as a result of alternation of the cube and pyritohedron faces. In Geometry, a pyritohedron is an irregular Dodecahedron. Like the regular dodecahedron it has twelve identical Pentagonal faces with three meeting in Pyrite also frequently occurs as octahedral crystals and as pyritohedra (a dodecahedron with pentagonal faces). An octahedron (plural octahedra is a Polyhedron with eight faces It has a slightly uneven and conchoidal fracture, a hardness of 6–6. The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material 5, and a specific gravity of 4. Specific gravity is defined as the ratio of the Density of a given solid or liquid substance to the density of water at a specific temperature and pressure typically 95–5. 10. [1] It is brittle and can be identified in the field by the distinctive odor released when samples are pulverized.
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. An oxide is a Chemical compound containing at least one Oxygen atom as well as at least one other element Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in In Geology, a vein is a finite volume within a rock, having a distinct shape filled with Crystals of one or more Minerals which were precipitated Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. Despite being nicknamed fool's gold, small quantities of gold are sometimes found associated with pyrite. Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 In fact, such auriferous pyrite is a valuable ore of gold. An ore is a volume of rock containing components or Minerals in a mode of occurrence that renders it valuable for mining
Weathering and release of sulfate
Pyrite exposed to the atmosphere during mining and excavation reacts with oxygen and water to form sulfate, resulting in acid mine drainage. Mining is the extraction of valuable Minerals or other geological materials from the earth usually (but not always from an Ore body Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Water is a common Chemical substance that is essential for the survival of all known forms of Life. Acid mine drainage ( AMD) or acid rock drainage ( ARD) refers to the outflow of Acidic water from (usually abandoned Metal mines This acidity results from the action of Acidithiobacillus bacteria, which generate their energy by oxidizing ferrous iron (Fe2+) to ferric iron (Fe3+) using oxygen. Acidithiobacillus is a genus of Proteobacteria. The members of this genus used to belong to Thiobacillus, before they were reclassified Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the The ferric iron in turn attacks the pyrite to produce ferrous iron and sulfate. The ferrous iron is then available for oxidation by the bacterium; this cycle continues until the pyrite is depleted.
Uses
Pyrite is used commercially for the production of sulfur dioxide, for use in such applications as the paper industry, and in the manufacture of sulfuric acid, although such applications are declining in importance.
Pyrite and marcasite
Pyrite is often confused with the mineral marcasite, a mineral whose name is derived from the Arabic word for pyrite, due to their similar characteristics. Euhedral Crystals are those that are well-formed with sharp easily-recognized faces The Mineral marcasite, sometimes called white iron pyrite, is Iron Sulfide (FeS2 Arabic (ar الْعَرَبيّة (informally ar عَرَبيْ) in terms of the number of speakers is the largest living member of the Semitic language Marcasite is a polymorph of pyrite, which means it has the same formula as pyrite but a different structure and, therefore, different symmetry and crystal shapes. Polymorphism in Materials science is the ability of a solid material to exist in more than one form or Crystal structure The formal oxidation states are, however, the same as in pyrite because again the sulfur atoms occur in persulfide-like pairs. [4] Marcasite/pyrite is probably the most famous polymorph pair next to the diamond/graphite pair. In Mineralogy, diamond is the allotrope of carbon where the carbon atoms are arranged in The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon. Appearance is slightly more silver.
Marcasite is metastable relative to pyrite and will slowly be changed to pyrite if heated or given enough time. Marcasite is relatively rare, but may be locally abundant in some types of ore deposits, such as Mississippi Valley-type Pb-Zn deposits. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Zinc (ˈzɪŋk from Zink is a Metallic Chemical element with the symbol Zn and Atomic number 30 Marcasite appears to form only from aqueous solutions.
Pyrite is often used in jewellery such as necklaces and bracelets, but although the two are similar, marcasite cannot be used in jewellery as it tends to crumble into powder. Jewellery (also spelled jewelry, see spelling differences) is a personal Ornament, such as a necklace ring or bracelet made from Gemstones Adding to the confusion between marcasite and pyrite is the use of the word marcasite as a jewellery trade name. The term is applied to small polished and faceted stones that are inlaid in sterling silver, but even though they are called marcasite, they actually contain pyrite. Facets are flat faces on geometric shapes The organization of naturally occurring facets was key to early developments in Crystallography, since they reflect the underlying Sterling silver is an Alloy of Silver containing 925% pure silver and 7
Formal oxidation states for pyrite, marcasite, and arsenopyrite
From the perspective of classical inorganic chemistry, which assigns formal oxidation states to each atom, pyrite is probably best described as Fe2+S22-. This formalism recognizes that the sulfur atoms in pyrite occur in pairs with clear S-S bonds. These persulfide units can be viewed as derived from hydrogen persulfide, H2S2. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Thus pyrite would be more descriptively called iron persulfide, not iron disulfide. In contrast, molybdenite, MoS2, features isolated sulfide (S2-) centers. Molybdenite is a mineral of Molybdenum disulfide, Mo[[sulfur S]]2 Molybdenum (məˈlɪbdənəm from the Greek word for the metal " Lead " is a Group 6 Chemical element with the symbol Mo Consequently, the oxidation state of molybdenum is Mo4+. The mineral arsenopyrite has the formula FeAsS. Arsenic (ˈɑrsənɪk is a Chemical element that has the symbol As and Atomic number of 33 Whereas pyrite has S2 subunits, arsenopyrite has AsS units, formally derived from deprotonation of H2AsSH. Deprotonation is a Chemistry term that refers to the removal of a Proton ( Hydrogen Cation H+ from a Molecule, forming Analysis of classical oxidation states would recommend the description of arsenopyrite as Fe3+AsS3-. [4]
Varieties
Bravoite is a nickel-cobalt bearing variety of pyrite, with >50% substitution of Ni2+ for Fe2+ within pyrite. Nickel (ˈnɪkəl is a metallic Chemical element with the symbol Ni and Atomic number 28 Bravoite is not a formally recognised mineral, and is named after Peruvian scientist Jose J. Bravo (1874-1928). [5]
References
- ^ a b Hurlbut, Cornelius S. ; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed. , John Wiley and Sons, New York, p 285-286, ISBN 0-471-80580-7
- ^ http://webmineral.com/data/Pyrite.shtml Webmineral
- ^ http://www.mindat.org/min-3314.html Pyrite on Mindat. org
- ^ a b Vaughan, D. J. ; Craig, J. R. “Mineral Chemistry of Metal Sulfides" Cambridge University Press, Cambridge: 1978. ISBN 0521214890.
- ^ http://www.mindat.org/min-759.html Mindat - bravoite
- American Geological Institute, 2003, Dictionary of Mining, Mineral, and Related Terms, 2nd ed. , Springer, New York, ISBN 978-3540012719
- Mineral galleries
External links
- How Minerals Form and Change "Pyrite oxidation under room conditions".
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