Sperrylite | |
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General | |
Category | Arsenide mineral Pyrite group |
Formula (repeating unit) | PtAs2 |
IMA symbol | Spy [1] |
Strunz classification | 2.EB.05a |
Crystal system | Isometric |
Crystal class | Diploidal (m3) H-M symbol: (2/m 3) |
Space group | Pa3 |
Unit cell | a = 5.967 Å, Z = 4 |
Identification | |
Color | Tin white |
Crystal habit | Well-formed finely crystalline, massive to reniform |
Cleavage | Indistinct on {001} |
Fracture | Conchoidal |
Tenacity | Brittle |
Mohs scale hardness | 6–7 |
Luster | Metallic |
Streak | Black |
Specific gravity | 10.58 |
References | [2] [3] [4] |
Sperrylite is a platinum arsenide mineral with the chemical formula PtAs2 and is an opaque metallic tin white mineral which crystallizes in the isometric system with the pyrite group structure. It forms cubic, octahedral or pyritohedral crystals in addition to massive and reniform habits. It has a Mohs hardness of 6–7 and a very high specific gravity of 10.6.
It was discovered by the American chemist Francis Louis Sperry in 1888-89 in ore from the Vermillion Mine, part of the Sudbury Basin discoveries, as he did a fire assay to determine the gold content of the ore for the Canadian Copper Company who were interested by the property. [5]
The most important occurrence of sperrylite is in the nickel ore deposit of Sudbury Basin in Ontario, Canada. It also occurs in the layered igneous complex of the Bushveld region of South Africa and the Oktyabr'skoye copper-nickel deposit near Noril'sk, Russia.
Sperrylite is the most common platinum mineral, it generally occurs with a wide array of other unusual minerals, including cooperite [(Pt,Pd,Ni)S], laurite [RuS2], kotulskite [Pd(Te,Bi)], merenskyite [(Pd,Pt)(Te,Bi)2], iridium-osmium (Ir-Os) alloys, sudburyite [(Pd,Ni)Sb], omeiite [(Os,Ru)As2], testibiopalladite [PdTe(Sb,Te)], and niggliite [PtSn], to name a few. It does not readily decompose through normal weathering processes and, consequently, has been reported in widely scattered alluvial deposits.
It was first found as tiny crystals found with rhodolite garnet and corundum during alluvial gem mining in streams draining Mason Mountain, Macon County, North Carolina (Hidden 1898). Sperrylite has been identified in Finland from sulfide deposits generally associated with layered mafic-ultramafic complexes.
Sperrylite belongs to the pyrite group of minerals and therefore it shares similar structure and crystal habits with them. Analyses typically show minor amounts of rhodium. Trace copper, iron, and antimony as well as intergrowths with Pt-Fe are reported from some occurrences. Sperrylite crystallizes in Pa3, with a =5.9681(l) A. (Szymański, 1979). It has very similar crystal structure as in platarsite (ideally PtAsS). Sperrylite crystals vary considerably in shape and size and are usually enclosed in a variety of host minerals. They are usually closely associated with basemetal sulfide. They are commonly at the edge and partially enclosed by pentlandite, pyrrhotite or chalcopyrite. Seabrook (2004).
Sperrylite is composed of loose aggregate of bright silver cubes, some with octahedral modifications. The grains are mostly anhedral, but a few euhedral grains could also be encountered. Sperrylite is formed by contact metamorphism, as in indicated by the development of triple point annealing contacts with pyrrhotite grains. The grains of sperrylite are surrounded by later veins of pyrite.
Sperrylite is cubic (2/m3) and is typically seen in well-developed cubes or cuboctahedra, some of which are so highly modified that crystal edges and comers appear rounded. (Nicol and Goldschmidt 1903) identified seventeen crystal forms exhibited by sperrylite, including four different trapezohedra, a trisoctahedron, five pyritohedra, and four diploids. Crystals to 2.5 cm have been reported.
Cell dimensions | a = 5.967, Z = 4; V = 212.46 Den(Calc)= 10.78 |
Crystal system | Isometric – Diploidal H-M Symbol (2/m 3) Space Group: P a3 |
X ray diffraction | By Intensity(I/Io): 1.801(1), 1.148(0.7), 2.98(0.6) |
Forms | [1 0 2] [1 1 1] [1 0 0] |
Sperrylite is a tin-white mineral known for its brilliant metallic luster, with a grey to black streak. It has indistinct cleavage on {001} and a conchoidal fracture and is brittle. Its hardness is between 6 and 7, and it is quite dense with a calculated specific gravity of 10.78. It has an isometric crystal structure, conchoidal fracture, is non-magnetic and non-radioactive.
Sperrylite was first described by H. H. Wells in 1889 from material collected at the Vermilion mine in what is now the Sudbury district, Ontario, Canada. He named it for Francis L. Sperry, chief chemist with the Canadian Copper Company of Sudbury, who collected the original material in 1887 (Mitchell 1985). It occurred in weathered material with colorless transparent cassiterite [SnO2], which is thought to have been derived from the oxidation of stannite [Cu2(Fe,Zn)SnS4].
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.
Pentlandite is an iron–nickel sulfide with the chemical formula (Fe,Ni)9S8. Pentlandite has a narrow variation range in nickel to iron ratios (Ni:Fe), but it is usually described as 1:1. In some cases, this ratio is skewed by the presence of pyrrhotite inclusions. It also contains minor cobalt, usually at low levels as a fraction of weight.
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.
The platinum-group metals (PGMs), also known as the platinoids, platinides, platidises, platinum group, platinum metals, platinum family or platinum-group elements (PGEs), are six noble, precious metallic elements clustered together in the periodic table. These elements are all transition metals in the d-block.
Nickeline or niccolite is the mineral form of nickel arsenide. The naturally-occurring mineral contains roughly 43.9% nickel and 56.1% arsenic by mass, but composition of the mineral may vary slightly.
Ullmannite or Nickel glance is a nickel antimony sulfide mineral with formula: NiSbS. Considerable substitution occurs with cobalt and iron in the nickel site along with bismuth and arsenic in the antimony site. A solid solution series exists with the high cobalt willyamite.
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 increases, 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.
The sulphide minerals are a class of minerals containing sulphide (S2−) or disulphide as the major anion. Some sulfide minerals are economically important as metal ores. The sulphide class also includes the selenides, the tellurides, the arsenides, the antimonides, the bismuthinides, the sulpharsenides and the sulphosalts. Sulphide minerals are inorganic compounds.
A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native deposits singly or in alloys include antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, manganese, molybdenum, nickel, niobium, rhenium, tantalum, tellurium, tin, titanium, tungsten, vanadium, and zinc, as well as the gold group and the platinum group. Among the alloys found in native state have been brass, bronze, pewter, German silver, osmiridium, electrum, white gold, silver-mercury amalgam, and gold-mercury amalgam.
Violarite (Fe2+Ni23+S4) is a supergene sulfide mineral associated with the weathering and oxidation of primary pentlandite nickel sulfide ore minerals.
Creighton Mine is an underground nickel, copper, and platinum-group elements (PGE) mine. It is presently owned and operated by Vale Limited in the city of Greater Sudbury, Ontario, Canada. Open pit mining began in 1901, and underground mining began in 1906. The mine is situated in the Sudbury Igneous Complex (SIC) in its South Range geologic unit. The mine is the source of many excavation-related seismic events, such as earthquakes and rock burst events. It is home to SNOLAB, and is currently the deepest nickel mine in Canada. Expansion projects to deepen the Creighton Mine are currently underway.
Carrollite, CuCo2S4, is a sulfide of copper and cobalt, often with substantial substitution of nickel for the metal ions, and a member of the linnaeite group. It is named after the type locality in Carroll County, Maryland, US, at the Patapsco mine, Sykesville.
The Lac des Îles igneous complex of northwestern Ontario, Canada is a layered gabbroic intrusion which is the host for the largest palladium orebody in Canada. The orebody is currently being mined as a combined open pit and underground operation by North American Palladium.
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.
Millerite or nickel blende 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.
The pyrite group of minerals is a set of cubic crystal system minerals with diploidal structure. Each metallic element is bonded to six "dumbbell" pairs of non-metallic elements and each "dumbbell" pair is bonded to six metal atoms.
Hidalgoite, PbAl3(AsO4)(SO4)(OH)4, is a rare member of the beudantite group and is usually classified as part of the alunite family. It was named after the place where it was first discovered, the Zimapán mining district, Hidalgo, Mexico. At Hidalgo where it was initially discovered, it was found as dense white masses in alternating dikes of quartz latite and quartz monzonite alongside other secondary minerals such as sphalerite, arsenopyrite, cerussite and trace amounts of angelsite and alamosite, it was then rediscovered at other locations such as Australia where it occurs on oxidized shear zones above greywacke shales especially on the anticline prospects of the area, and on fine grained quartz-spessartine rocks in Broken Hill, Australia. Hidalgoite specimens are usually associated with copper minerals, clay minerals, iron oxides and polymetallic sulfides in occurrence.
Chvilevaite (Russian: чвилеваи́т, чвилёваи́т, in its own name) is a rare hydrothermal polymetallic mineral from the class of complex sulfides, forming microscopic grains in related minerals, its composition is a rare combination of alkali (combining lithophile) and chalcophile metals — sodium ferro-sulfide, zinc and copper with the calculation formula Na(Cu,Fe,Zn)2S4, originally published and confirmed as Na(Cu,Fe,Zn)2S2.
Frohbergite (German: Frohbergit, title by proper name: Max Hans Frohberg), also iron telluride is a rare hydrothermal mineral from the sulfide class, in composition — iron telluride with the ideal formula FeTe2 (contains 82.05% tellurium and 17.95% iron).