Walfordite | |
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General | |
Category | Tellurite minerals |
Formula (repeating unit) | Fe3+,Te6+Te4+3O8 |
IMA symbol | wfd [1] |
Strunz classification | 4.JK.05 |
Crystal system | Isometric |
Space group | I2, Ia3 |
Unit cell | a = 11.011 Å ; Z = 8 |
Identification | |
Colour | Orange |
Crystal habit | Microscopic cubic crystals |
Cleavage | None |
Tenacity | Brittle |
Luster | Adamantine |
Streak | Orange-yellow |
Diaphaneity | Opaque |
Specific gravity | 5.841 (calculated) |
Optical properties | Isotropic |
Refractive index | n = 2.23 |
References | [2] [3] [4] |
Walfordite is a very rare tellurite mineral that was discovered in Chile in 1999. [5] The mineral is described as orange with orange-yellow streak, and is determined to have a chemical formula of Fe3+,Te6+Te4+3O8 [2] with minor titanium and magnesium substitution resulting in an approximate empirical formula of (Fe3+,Te6+,Ti4+,Mg)(Te4+)3O8. [5]
The only reported occurrence [3] is in the Wendy open pit, El Indio-Tambo mining district of the Coquimbo Region, northern Chile where it occurs in oxidized breccia associated with a tellurium-bearing gold deposit. Associated minerals include: alunite, rodalquilarite, native gold, emmonsite, jarosite and pyrite. The mineral was named for mine geologist Phillip Walford (1945— ) who first noted the mineral. [2]
Copiapite is a hydrated iron sulfate mineral with formula: Fe2+Fe3+4(SO4)6(OH)2·20(H2O). Copiapite can also refer to a mineral group, the copiapite group.
Galaxite, also known as 'mangan-spinel' is an isometric mineral belonging to the spinel group of oxides with the ideal chemical formula Mn2+Al2O4.
Jacobsite is a manganese iron oxide mineral. It is in the spinel group and forms a solid solution series with magnetite. The chemical formula is (Mn,Mg)Fe2O4 or with oxidation states and substitutions: (Mn2+,Fe2+,Mg)(Fe3+,Mn3+)2O4.
Zincobotryogen is a hydrous sulfate mineral with the chemical formula (Zn,Mg,Mn)Fe3+(SO4)2(OH)·7H2O. It forms bright orange red monoclinic prismatic crystals that exhibit a vitreous to greasy luster. Its specific gravity is 2.201 and it has a Mohs hardness of 2.5.
Cesbronite is a copper-tellurium oxysalt mineral with the chemical formula Cu3Te6+O4(OH)4 (IMA 17-C). It is colored green and its crystals are orthorhombic dipyramidal. Cesbronite is rated 3 on the Mohs Scale. It is named after Fabien Cesbron (born 1938), a French mineralogist.
Aheylite is a rare phosphate mineral with formula (Fe2+Zn)Al6[(OH)4|(PO4)2]2·4(H2O). It occurs as pale blue to pale green triclinic crystal masses. Aheylite was made the newest member of the turquoise group in 1984 by International Mineralogical Association Commission on New Minerals and Mineral Names.
Piemontite is a sorosilicate mineral in the monoclinic crystal system with the chemical formula Ca2(Al,Mn3+,Fe3+)3(SiO4)(Si2O7)O(OH). It is a member of the epidote group.
Cafarsite is a rare calcium iron arsenite mineral. Manganese and titanium occur with iron in the formula.
Zemannite is a very rare oxide mineral with the chemical formula Mg0.5ZnFe3+[TeO3]3·4.5H2O. It crystallizes in the hexagonal crystal system and forms small prismatic brown crystals. Because of the rarity and small crystal size, zemannite has no applications and serves as a collector's item.
Emmonsite, also known as durdenite, is an iron tellurite mineral with the formula: Fe2(TeO3)3·2(H2O). Emmonsite forms triclinic crystals. It is of a yellowish-green color, with a vitreous luster, and a hardness of 5 on the Moh scale.
Amarantite is an amaranth-red to brownish mineral with the general formula of Fe3+2O(SO4)2·7H2O or Fe3+SO4(OH)·3H2O.
The El Indio Gold Belt is a mineral-rich region spanning the border between Chile and Argentina that contains large quantities of gold, silver and copper. On both sides of the border the belt is located within the Andes. The El Indio mine within the district was the first modern mine in Chile to produce gold as its main product. In Chile the main precious metal containing mineral is enargite. The El Indio belt is bordered in the north by another gold-silver mining district known as the Frontera District. Rodalquilarite, alunite and poughite are some of the minerals present in the area. The deposits of the belt formed during the Late Miocene period.
Utahite is an extremely rare secondary copper zinc tellurate mineral found as a product of oxidation. Its chemical formula is Cu5Zn3(Te6+O4)4(OH)8•7H2O.
Ferrimolybdite is a hydrous iron molybdate mineral with formula: Fe3+2(MoO4)3·8(H2O) or Fe3+2(MoO4)3·n(H2O). It forms coatings and radial aggregates of soft yellow needles which crystallize in the orthorhombic system.
Rodalquilarite is a rare iron tellurite chloride mineral with formula H3Fe3+2(Te4+O3)4Cl or Fe2(TeO2OH)3(TeO3)Cl. Rodalquilarite crystallizes in the triclinic system and typically occurs as stout green prisms and encrustations.
Tlapallite is a rare and complex tellurate mineral with the chemical formula (Ca,Pb)3CaCu6[Te4+3Te6+O12]2(Te4+O3)2(SO4)2·3H2O. It has a Moh's hardness of 3 and it is green in colour. It was named after the Nahua word "Tlalpalli", which translates to paint, referring to the paint-like habit of the mineral. Its formula and crystal structure were redefined in 2019, showing it contained a mixed-valence phyllotellurate layer [Te4+3Te6+O12]12−.
Carlfriesite is a rare tellurium mineral with the formula CaTe4+2Te6+O8, or more simplified: CaTe3O8. It has a Moh's hardness of 3.5 and it occurs in various shades of yellow, ranging from bright yellow to a light buttery color. It was named after Carl Fries Jr. (1910–1965) from the U.S. Geological Survey and the Geological Institute of the National University, Mexico City, Mexico. It was previously thought to have the formula H4Ca(TeO3)3, but this was proven to be incorrect. It has no uses beyond being a collector's item.
Teineite is a tellurite mineral with the formula Cu(TeO3). 2 H2O. It has a Mohs hardness of 2.5 and it comes in many different shades of blue, ranging from cerulean blue to bluish-gray. The mineral millsite has the same chemical composition, but crystallizes in the monoclinic system, while teineite crystallizes in the orthorhombic system.
Lemanskiite is a mineral that was first discovered in a mine at Abundancia mine, El Guanaco mining district, Chile, with the ideal formula of NaCaCu5(AsO4)4Cl•3H2O. Originally, this mineral was discovered as being dimorphus with lavendulan, but in 2018 it was revised to only have 3 water molecules. Lemanskiite typically occurs as rosette-shaped aggregates of thin lamellar or needle-shaped aggregates, such as lammerite. Lemanskiite is dark sky blue with a light blue streak, it is brittle with an excellent cleavage plane. It was found on a dumping site in the abandoned Abundancia mine, El Guanaco mining district, Region II, Antofagasta Province, Chile The new mineral has been named after Chester S. Lemanski, Jr. This mineral and name were then approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association.
Northstarite is an immensely rare lead-tellurite-thiosulfate mineral with an ideal formula of Pb6(Te4+ O3)5(S6+O3S2-). Northstarite was first discovered in 2019 by Charles Adan in the North Star Mine of the Tintic Mining District, Juab County, Utah, USA. Northstarite received its name after this type locality where it was originally discovered, the North Star Mine. Northstarite is the fourth thiosulfate mineral that exists on Earth, and although all thiosulfates have essential lead components, northstarite is the first thiosulfate species containing groups of both thiosulfate and tellurite (Te4+O3).