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.
Germanite is a rare copper iron germanium sulfide mineral, Cu26Fe4Ge4S32. It was first discovered in 1922, and named for its germanium content. It is only a minor source of this important semiconductor element, which is mainly derived from the processing of the zinc sulfide mineral sphalerite. Germanite contains gallium, zinc, molybdenum, arsenic, and vanadium as impurities.
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.
Bukovskyite (also known as "clay of Kutná Hora") is an iron arsenate sulfate mineral with formula: Fe2(AsO4)(SO4)(OH)·7H2O which forms nodules with a reniform (kidney-shaped) surface. Under a microscope, these nodules appear as a collection of minute needles similar to gypsum. Some can be seen with the naked eye and occur inside the nodules.
Mimetite is a lead arsenate chloride mineral (Pb5(AsO4)3Cl) which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name derives from the Greek Μιμητής mimetes, meaning "imitator" and refers to mimetite's resemblance to the mineral pyromorphite. This resemblance is not coincidental, as mimetite forms a mineral series with pyromorphite (Pb5(PO4)3Cl) and with vanadinite (Pb5(VO4)3Cl). Notable occurrences are Mapimi, Durango, Mexico and Tsumeb, Namibia.
Adamite is a zinc arsenate hydroxide mineral, Zn2AsO4OH. It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Pure adamite is colorless, but usually it possess yellow color due to Fe compounds admixture. Tints of green also occur and are connected with copper substitutions in the mineral structure. Olivenite is a copper arsenate that is isostructural with adamite and there is considerable substitution between zinc and copper resulting in an intermediate called cuproadamite. Zincolivenite is a recently discovered mineral being an intermediate mineral with formula CuZn(AsO4)(OH). Manganese, cobalt, and nickel also substitute in the structure. An analogous zinc phosphate, tarbuttite, is known.
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.
Freibergite is a complex sulfosalt mineral of silver, copper, iron, antimony and arsenic with formula (Ag,Cu,Fe)12(Sb,As)4S13. It has cubic crystals and is formed in hydrothermal deposits. It forms one solid solution series with tetrahedrite and another with argentotennantite. Freibergite is an opaque, metallic steel grey to black and leaves a reddish-black streak. It has a Mohs hardness of 3.5 to 4.0 and a specific gravity of 4.85 to 5. It is typically massive to granular in habit with no cleavage and an irregular fracture.
Geocronite is a mineral, a mixed sulfosalt containing lead, antimony, and arsenic with a formula of Pb14(Sb, As)6S23. Geocronite is the antimony-rich endmember of a solid solution series. The arsenic-rich endmember is named jordanite. It occurs as grey, black, to silvery white monoclinic crystals. It is found in hydrothermal veins usually associated with other similar minerals, particularly the sulfides of iron and copper.
Glaucodot is a cobalt iron arsenic sulfide mineral with formula (Co,Fe)AsS. The cobalt:iron(II) ratio is typically 3:1 with minor nickel substituting. It forms a series with arsenopyrite (FeAsS). It is an opaque grey to tin-white typically found as massive forms without external crystal form. It crystallizes in the orthorhombic system. The locality at Håkansboda, Sweden has rare twinned dipyramidal crystals. It is brittle with a Mohs hardness of 5 and a specific gravity of 5.95. It occurs in high temperature hydrothermal deposits with pyrrhotite and chalcopyrite. Glaucodot is classed as a sulfide in the arsenopyrite löllingite group.
Pharmacosiderite is a hydrated basic ferric arsenate, with the chemical formula KFe4(AsO4)3(OH)4·(6-7)H2O and a molecular weight of 873.38 g/mol. It consists of the elements arsenic, iron, hydrogen, potassium, sodium and oxygen. It has a Mohs hardness of 2 to 3, about that of a finger nail. Its specific gravity is about 2.7 to 2.9, has indistinct cleavage, and is usually transparent or translucent. It has a yellow or white streak and a yellow, green, brown or red color. Its lustre is adamantine, vitreous and resinous, and it has conchoidal, brittle and sectile fracture.
Kankite is a mineral with the chemical formula Fe3+AsO4·3.5(H2O). Kankite is named for the locality that yielded first specimens Kaňk, Czech Republic. Kankite forms in old (1200- to 1400-year-old) mine dumps. It is yellowish-green on fresh exposure, with a paler greenish yellow on exposure to air.
Arsenolite is an arsenic mineral, chemical formula As4O6. It is formed as an oxidation product of arsenic sulfides. Commonly found as small octahedra it is white, but impurities of realgar or orpiment may give it a pink or yellow hue. It can be associated with its dimorph claudetite (a monoclinic form of As2O3) as well as realgar (As4S4), orpiment (As2S3) and erythrite, Co3(AsO4)2·8H2O.
Robertsite, Ca3(Mn3+)4[(OH)3| (PO4)2]2·3(H2O) (alternatively formulated Ca2(Mn3(PO4)3O2)(H2O)3), is a secondary phosphate mineral named for Willard Lincoln Roberts (1923–1987), mineralogist and professor at South Dakota School of Mines in Rapid City, South Dakota.
Cafarsite is a rare calcium iron arsenite mineral. Manganese and titanium occur with iron in the formula.
Beudandite is a secondary mineral occurring in the oxidized zones of polymetallic deposits. It is a lead, iron, arsenate, sulfate with endmember formula: PbFe3(OH)6SO4AsO4.
Gatehouseite is a manganese hydroxy phosphate mineral with formula Mn5(PO4)2(OH)4. First discovered in 1987, it was identified as a new mineral species in 1992 and named for Bryan M. K. C. Gatehouse (born 1932). As of 2012, it is known from only one mine in South Australia.
Carminite (PbFe3+2(AsO4)2(OH)2) is an anhydrous arsenate mineral containing hydroxyl. It is a rare secondary mineral that is structurally related to palermoite (Li2SrAl4(PO4)4(OH)4). Sewardite (CaFe3+2(AsO4)2(OH)2) is an analogue of carminite, with calcium in sewardite in place of the lead in carminite. Mawbyite is a dimorph (same formula, different structure) of carminite; mawbyite is monoclinic and carminite is orthorhombic. It has a molar mass of 639.87 g. It was discovered in 1850 and named for the characteristic carmine colour.
Szklaryite is an extremely rare mineral with the formula []Al6BAs33+O15. It is essentially vacant ("[]"), arsenic-dominant member of dumortierite supergroup, giving a name of szklaryite group. It is one of three quite recently found minerals of this group, the other two being nioboholtite and titanoholtite, all coming from the Szklary village near Ząbkowice Śląskie in Poland. They occur in a unique pegmatite of probable anatectic origin.
Parascorodite is a rare, secondary iron-arsenate mineral. It has a chemical formula of (FeAsO4·2H2O) and was discovered in 1967 using X-ray powder diffraction methods, when an unknown substance was found along with scorodite on medieval ore dumps in the Czech Republic. The holotype of parascorodite can be found in the mineralogical collection of the National Museum, Prague, Czech Republic under acquisition number P1p25/98.
