The mineral pyrite ( PY-ryte), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula FeS2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral.
Arsenopyrite is an iron arsenic sulfide (FeAsS). It is a hard 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 produces sulfur and arsenic vapor. With 46% arsenic content, arsenopyrite, along with orpiment, is a principal ore of arsenic. When deposits of arsenopyrite become exposed to the atmosphere, the mineral slowly converts into iron arsenates. Arsenopyrite is generally an acid-consuming sulfide mineral, unlike iron pyrite which can lead to acid mine drainage.
Chalcopyrite ( KAL-kə-PY-ryte, -koh-) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green-tinged black.
Bornite, also known as peacock ore, is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system (pseudo-cubic).
The mineral petzite, Ag3AuTe2, is a soft, steel-gray telluride mineral generally deposited by hydrothermal activity. It forms isometric crystals, and is usually associated with rare tellurium and gold minerals, often with silver, mercury, and copper.
Molybdenite is a mineral of molybdenum disulfide, MoS2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum atoms sandwiched between sheets of sulfur atoms. The Mo-S bonds are strong, but the interaction between the sulfur atoms at the top and bottom of separate sandwich-like tri-layers is weak, resulting in easy slippage as well as cleavage planes. Molybdenite crystallizes in the hexagonal crystal system as the common polytype 2H and also in the trigonal system as the 3R polytype.
Nickeline or niccolite is a mineral consisting primarily of nickel arsenide (NiAs). The naturally-occurring mineral contains roughly 43.9% nickel and 56.1% arsenic by mass, but composition of the mineral may vary slightly.
Covellite is a rare copper sulfide mineral with the formula CuS. This indigo blue mineral is commonly a secondary mineral in limited abundance and although it is not an important ore of copper itself, it is well known to mineral collectors.
Pyrrhotite is an iron sulfide mineral with the formula Fe(1-x)S. It is a nonstoichiometric variant of FeS, the mineral known as troilite. Pyrrhotite is also called magnetic pyrite, because the color is similar to pyrite and it is weakly magnetic. The magnetism decreases as the iron content decreases, and troilite is non-magnetic. Pyrrhotite is generally tabular and brassy/bronze in color with a metallic luster. The mineral occurs with mafic igneous rocks like norites, and may form from pyrite during metamorphic processes. Pyrrhotite is associated and mined with other sulfide minerals like pentlandite, pyrite, chalcopyrite, and magnetite, and has been found globally.
The mineral marcasite, sometimes called "white iron pyrite", is iron sulfide (FeS2) with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Both structures contain the disulfide S22− ion, having a short bonding distance between the sulfur atoms. The structures differ in how these di-anions are arranged around the Fe2+ cations. Marcasite is lighter and more brittle than pyrite. Specimens of marcasite often crumble and break up due to the unstable crystal structure.
Wurtzite is a zinc and iron sulfide mineral with the chemical formula (Zn,Fe)S, a less frequently encountered structural polymorph form of sphalerite. The iron content is variable up to eight percent. It is trimorphous with matraite and sphalerite.
Cobaltite is a sulfide mineral composed of cobalt, arsenic, and sulfur, CoAsS. It naturally appears in the form of a tetartoid, a form of dodecahedron with chiral tetrahedral symmetry. Its impurities may contain up to 10% iron and variable amounts of nickel. Structurally, it resembles pyrite (FeS2) with one of the sulfur atoms replaced by an arsenic atom.
Laurite is an opaque black, metallic ruthenium sulfide mineral with formula: RuS2. It crystallizes in the isometric system. It is in the pyrite structural group. Though it's been found in many localities worldwide, it is extremely rare.
Troilite is a rare iron sulfide mineral with the simple formula of FeS. It is the iron-rich endmember of the pyrrhotite group. Pyrrhotite has the formula Fe(1-x)S which is iron deficient. As troilite lacks the iron deficiency which gives pyrrhotite its characteristic magnetism, troilite is non-magnetic.
A chalcogenide is a chemical compound consisting of at least one chalcogen anion and at least one more electropositive element. Although all group 16 elements of the periodic table are defined as chalcogens, the term chalcogenide is more commonly reserved for sulfides, selenides, tellurides, and polonides, rather than oxides. Many metal ores exist as chalcogenides. Photoconductive chalcogenide glasses are used in xerography. Some pigments and catalysts are also based on chalcogenides. The metal dichalcogenide MoS2 is a common solid lubricant.
In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Supergene processes include the predominance of meteoric water circulation (i.e. water derived from precipitation) with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary. The reaction produces secondary sulfides with metal contents higher than those of the primary ore. This is particularly noted in copper ore deposits where the copper sulfide minerals chalcocite (Cu2S), covellite (CuS), digenite (Cu18S10), and djurleite (Cu31S16) are deposited by the descending surface waters.
Cattierite (CoS2) is a cobalt sulfide mineral found in the Democratic Republic of Congo. It was discovered together with the nickel sulfide vaesite by Johannes F. Vaes, a Belgian mineralogist and named after Felicien Cattier, who was chairman of the board of the Union Minière du Haut-Katanga.
Cubanite is a copper iron sulfide mineral that commonly occurs as a minor alteration mineral in magmatic sulfide deposits. It has the chemical formula CuFe2S3 and when found, it has a bronze to brass-yellow appearance. On the Mohs hardness scale, cubanite falls between 3.5 and 4 and has a orthorhombic crystal system. Cubanite is chemically similar to chalcopyrite; however, it is the less common copper iron sulfide mineral due to crystallization requirements.
Patrónite is the vanadium sulfide mineral with formula VS4. The material is usually described as V4+(S22−)2. Structurally, it is a "linear-chain" compound with alternating bonding and nonbonding contacts between the vanadium centers. The vanadium is octa-coordinated, which is an uncommon geometry for this metal.
Millerite is a nickel sulfide mineral, NiS. It is brassy in colour and has an acicular habit, often forming radiating masses and furry aggregates. It can be distinguished from pentlandite by crystal habit, its duller colour, and general lack of association with pyrite or pyrrhotite.
