Cornwallite | |
---|---|
General | |
Category | Arsenate mineral |
Formula (repeating unit) | Cu5(AsO4)2(OH)4 |
IMA symbol | Cnw [1] |
Strunz classification | 8.BD.05 |
Dana classification | 41.4.2.2 |
Crystal system | Monoclinic |
Crystal class | Prismatic (2/m) (same H-M symbol) |
Space group | P21/c |
Unit cell | a = 17.33 Å, b = 5.82 Å, c = 4.60 Å; β = 92.22°; Z = 2 |
Identification | |
Color | Verdigis green, blackish-green, emerald-green |
Crystal habit | Microcrystalline radial fibrous, botryoidal to globular crusts |
Cleavage | Distinct in one direction |
Fracture | Conchoidal |
Tenacity | Brittle |
Mohs scale hardness | 4.5 |
Luster | Sub-vitreous, resinous, waxy |
Streak | Apple green |
Diaphaneity | Translucent to opaque |
Specific gravity | 4.17 |
Optical properties | Biaxial (+/−) |
Refractive index | nα = 1.810 – 1.820 nβ = 1.815 – 1.860 nγ = 1.850 – 1.880 |
Birefringence | δ = 0.040 – 0.060 |
2V angle | Measured: 30° to 50° |
References | [2] [3] [4] [5] |
Cornwallite is an uncommon copper arsenate mineral with formula Cu5(AsO4)2(OH)4. It forms a series with the phosphate pseudomalachite and is a dimorph of the triclinic cornubite. It is a green monoclinic mineral which forms as radial to fibrous encrustations.
It was first described in 1846, for an occurrence in Wheal Gorland, St Day United Mines of the St Day District, Cornwall, England. [4] It occurs as secondary mineral in the oxidized zone of copper sulfide deposits. Associated minerals include olivenite, cornubite, arthurite, clinoclase, chalcophyllite, strashimirite, lavendulan, tyrolite, spangolite, austinite, conichalcite, brochantite, azurite and malachite. [3]
Bornite, also known as peacock ore, is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system (pseudo-cubic).
Clinoclase is a hydrous copper arsenate mineral, Cu3AsO4(OH)3. Clinoclase is a rare secondary copper mineral and forms acicular crystals in the fractured weathered zone above copper sulfide deposits. It occurs in vitreous, translucent dark blue to dark greenish blue colored crystals and botryoidal masses. The crystal system is monoclinic 2/m. It has a hardness of 2.5–3 and a relative density of 4.3. Associated minerals include malachite, olivenite, quartz, limonite, adamite, azurite, and brochantite among others.
Chalcocite, copper(I) sulfide (Cu2S), is an important copper ore mineral. It is opaque and dark gray to black, with a metallic luster. It has a hardness of 2.5–3 on the Mohs scale. It is a sulfide with a monoclinic crystal system.
Cuprite is an oxide mineral composed of copper(I) oxide Cu2O, and is a minor ore of copper.
Erythrite or red cobalt is a secondary hydrated cobalt arsenate mineral with the formula Co
3(AsO
4)
2•8H
2O. Erythrite and annabergite, chemical formula Ni
3(AsO
4)
2•8H
2O, or nickel arsenate form a complete series with the general formula (Co,Ni)
3(AsO
4)
2•8H
2O.
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.
Olivenite is a copper arsenate mineral, formula Cu2AsO4OH. It crystallizes in the monoclinic system (pseudo-orthorhombic), and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces. More commonly, it occurs as globular aggregates of acicular crystals, these fibrous forms often having a velvety luster; sometimes it is lamellar in structure, or soft and earthy.
Stannite is a mineral, a sulfide of copper, iron, and tin, in the category of thiostannates.
Bournonite is a sulfosalt mineral species, trithioantimoniate of lead and copper with the formula PbCuSbS3.
Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu2Al[(OH)4|AsO4]·4(H2O). It is a vitreous monoclinic mineral, colored bright blue to green, often associated with malachite, azurite, olivenite, and clinoclase. It is quite soft, with a Mohs hardness of 2–2.5, and has a specific gravity of 2.9–3.0.
Aerugite is a rare complex nickel arsenate mineral with a variably reported formula: Ni9(AsO4)2AsO6. It forms green to deep blue-green trigonal crystals. It has a Mohs hardness of 4 and a specific gravity of 5.85 to 5.95.
Connellite is a rare mineral species, a hydrous copper chloro-sulfate, Cu19(OH)32(SO4)Cl4·3H2O, crystallizing in the hexagonal system. It occurs as tufts of very delicate acicular crystals of a fine blue color, and is associated with other copper minerals of secondary origin, such as cuprite and malachite. Its occurrence in Cornwall, England, was noted by Philip Rashleigh in 1802, and it was first examined chemically by Prof Arthur Connell FRSE in 1847, after whom it is named.
Arthurite is a mineral composed of divalent copper and iron ions in combination with trivalent arsenate, phosphate and sulfate ions with hydrogen and oxygen. Initially discovered by Sir Arthur Russell in 1954 at Hingston Down Consols mine in Calstock, Cornwall, England, arthurite is formed as a resultant mineral in the oxidation region of some copper deposits by the variation of enargite or arsenopyrite. The chemical formula of Arthurite is CuFe23+(AsO4,PO4,SO4)2(O,OH)2·4H2O.
Botallackite, chemical formula Cu2(OH)3Cl is a secondary copper mineral, named for its type locality at the Botallack Mine, St Just in Penwith, Cornwall. It is polymorphous with atacamite, paratacamite and clinoatacamite.
Chalcophyllite is a rare secondary copper arsenate mineral occurring in the oxidized zones of some arsenic-bearing copper deposits. It was first described from material collected in Germany. At one time chalcophyllite from Wheal Tamar in Cornwall, England, was called tamarite, but this name is now discredited. At Wheal Gorland a specimen exhibiting partial replacement of liriconite, Cu
2Al(AsO
4)(OH)
4·(4H
2O), by chalcophyllite has been found. The mineral is named from the Greek, chalco "copper" and fyllon, "leaf", in allusion to its composition and platy structure. It is a classic Cornish mineral that can be confused with tabular spangolite.
Conichalcite, CaCu(AsO4)(OH), is a relatively common arsenate mineral related to duftite (PbCu(AsO4)(OH)). It is green, often botryoidal, and occurs in the oxidation zone of some metal deposits. It occurs with limonite, malachite, beudantite, adamite, cuproadamite, olivenite and smithsonite.
Cornubite is a rare secondary copper arsenate mineral with formula: Cu5(AsO4)2(OH)4. It was first described for its discovery in 1958 in Wheal Carpenter, Gwinear, Cornwall, England, UK. The name is from Cornubia, the medieval Latin name for Cornwall. It is a dimorph of cornwallite, and the arsenic analogue of pseudomalachite.
Langite is a rare hydrated copper sulfate mineral, with hydroxyl, found almost exclusively in druses of small crystals. It is formed from the oxidation of copper sulfides, and was first described in specimens from Cornwall, United Kingdom. It is dimorphous with wroewolfeite. Langite was discovered in 1864 and named after the physicist and crystallographer Viktor von Lang (1838–1921), who was Professor of Physics at the University of Vienna, Austria.
Strashimirite is a rare monoclinic mineral containing arsenic, copper, hydrogen, and oxygen. It has the chemical formula Cu8(AsO4)4(OH)4·5(H2O).
Bieberite (CoSO4 · 7H2O) is a pinkish red colored sulfate mineral high in cobalt content. The name is derived from the type locality at the copper deposit in Bieber, Hesse, Germany. It has been described and reported as far back as the 1700s. Bieberite primarily occurs as a secondary mineral, forming in cobalt-bearing arsenide and sulfide deposits through oxidation.