Triclinic minerals

Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue.

Feldspar ( ; sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the plagioclase (sodium-calcium) feldspars and the alkali (potassium-sodium) feldspars. Feldspars make up about 60% of the Earth's crust and 41% of the Earth's continental crust by weight.

Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula . Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thickening agent and lubricant. It is an ingredient in ceramics, paints, and roofing material. It is a main ingredient in many cosmetics. It occurs as foliated to fibrous masses, and in an exceptionally rare crystal form. It has a perfect basal cleavage and an uneven flat fracture, and it is foliated with a two-dimensional platy form.

Kaolinite ( ; also called kaolin) is a clay mineral, with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral, with one "tetrahedral" sheet of silicate tetrahedra () linked to one "octahedral" sheet of aluminate octahedrons () through oxygen atoms on one side, and another such sheet through hydrogen bonds on the other side.

Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. It represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula . It is a tectosilicate. Its color is usually pure white, hence its name from Latin, . It is a common constituent in felsic rocks.

Kyanite is a typically blue aluminosilicate mineral, found in aluminium-rich metamorphic pegmatites and sedimentary rock. It is the high pressure polymorph of andalusite and sillimanite, and the presence of kyanite in metamorphic rocks generally indicates metamorphism deep in the Earth's crust. Kyanite is also known as disthene or cyanite.

Labradorite ((Ca, Na)(Al, Si)4O8) is a calcium-enriched feldspar mineral first identified in Labrador, Canada, which can display an iridescent effect (schiller).

Anorthite (2Si2O8. Anorthite is found in igneous rocks.

thumb|Plagioclase displaying cleavage (crystal)|cleavage (unknown scale) thumb|In volcanic rocks, [[fine-grained plagioclase can display a "microlitic" texture of many small crystals.]]

Wollastonite is a calcium inosilicate mineral (CaSiO3) that may contain small amounts of iron, magnesium, and manganese substituting for calcium. It is usually white. It forms when impure limestone or dolomite is subjected to high temperature and pressure, which sometimes occurs in the presence of silica-bearing fluids as in skarns or in contact with metamorphic rocks. Associated minerals include garnets, vesuvianite, diopside, tremolite, epidote, plagioclase feldspar, pyroxene and calcite. It is named after the English chemist and mineralogist William Hyde Wollaston (1766–1828).

Rhodonite is a manganese inosilicate, with the formula (Mn, Fe, Mg, Ca)SiO3, and member of the pyroxenoid group of minerals, crystallizing in the triclinic system. The term rhodonite was first introduced by Germar. . It commonly occurs as cleavable to compact masses with a rose-red color often tending to brown due to surface oxidation. The rose-red hue is caused by the manganese cation (Mn). thumb|left|Pink rhodonite contrasting with black manganese oxides is sometimes used as gemstone material as seen in this specimen from Humboldt County, [[Nevada.]] Rhodonite crystals often have a thick tab

Microcline (KAlSi3O8) is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. It is common in granite and pegmatites. Microcline forms during slow cooling of orthoclase. Sanidine is a polymorph of alkali feldspar stable at yet higher temperature. Microcline has cross-hatch twinning that forms as a result of the transformation of monoclinic orthoclase into triclinic microcline.

Chalcanthite (, ) is a richly colored blue-green water-soluble sulfate mineral . It is commonly found in the late-stage oxidation zones of copper deposits. Due to its ready solubility, chalcanthite is more common in arid regions.

Andesine is a silicate mineral, a member of the plagioclase feldspar solid solution series. Its chemical formula is (Ca, Na)(Al, Si)4O8, where the ratio of albite to anorthite (Na:Ca) is 50:50 to 70:30. The formula may be written as Na0.5-0.7Ca0.3-0.5Al1.3-1.5Si2.5-2.7O8.

Axinite is a brown to violet-brown, or reddish-brown bladed group of minerals composed of calcium aluminium boro-silicate, . Axinite is pyroelectric and piezoelectric.

Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters it is intermediate between albite (NaAlSi3O8) and anorthite (CaAl2Si2O8). The albite:anorthite molar ratio of oligoclase ranges from 90:10 to 70:30.

Bytownite is a calcium rich member of the plagioclase solid solution series of feldspar minerals with composition between anorthite and labradorite. It is usually defined as having between 70 and 90%An (formula: ). Like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations.

Ulexite (), sometimes called TV rock or TV stone due to its unusual optical properties, is a hydrous borate hydroxide of sodium and calcium with the chemical formula . The mineral occurs as silky white rounded crystalline masses or in parallel fibers. Ulexite was named for the German chemist Georg Ludwig Ulex (1811–1883), who first discovered it.

Pyrophyllite is a phyllosilicate mineral composed of aluminium silicate hydroxide: Al2Si4O10(OH)2. It occurs in two forms (habits): crystalline folia and compact masses; distinct crystals are not known.

Abelsonite is a nickel porphyrin mineral with chemical formula C31H32N4Ni. It was discovered in 1969 in the U.S. State of Utah and described in 1975. The mineral is named after geochemist Philip H. Abelson. It is the only known crystalline geoporphyrin.

Amblygonite () is a fluorophosphate mineral, , composed of lithium, sodium, aluminium, phosphate, fluoride and hydroxide. The mineral occurs in pegmatite deposits and is easily mistaken for albite and other feldspars. Its density, cleavage and flame test for lithium are diagnostic. Amblygonite forms a series with montebrasite, the low fluorine endmember. Geologic occurrence is in granite pegmatites, high-temperature tin veins, and greisens. Amblygonite occurs with spodumene, apatite, lepidolite, tourmaline, and other lithium-bearing minerals in pegmatite veins. It contains about 10% lithium, a

Sassolite is a borate mineral, specifically the mineral form of boric acid. It is usually white to gray, and colourless in transmitted light. It can also take on a yellow colour from sulfur impurities, or brown from iron oxides.

Astrophyllite is a very rare, brown to golden-yellow hydrous potassium iron titanium silicate mineral. Belonging to the astrophyllite group, astrophyllite may be classed either as an inosilicate, phyllosilicate, or an intermediate between the two. It forms an isomorphous series with kupletskite, to which it is visually identical and often intimately associated. Astrophyllite is of interest primarily to scientists and collectors.

Pectolite is a white to gray mineral, NaCa2Si3O8(OH), a sodium calcium hydroxide inosilicate. It crystallizes in the triclinic system typically occurring in radiated or fibrous crystalline masses. It has a Mohs hardness of 4.5 to 5 and a specific gravity of 2.7 to 2.9. A highly sought-after variety known as larimar, is a pale to sky blue. There is also a whitish form of the mineral from Alaska that is sometimes marketed as 'Alaska jade'.

Polyhalite is an evaporite mineral, a hydrated sulfate of potassium, calcium and magnesium with formula: . Polyhalite crystallizes in the triclinic system, although crystals are very rare. The normal habit is massive to fibrous. It is typically colorless, white to gray, although it may be brick red due to iron oxide inclusions. It has a Mohs hardness of 3.5 and a specific gravity of 2.8. It is used as a valuable fertilizer.

Kermesite (also known as antimony oxysulfide, red antimony, or purpur blende) is a mineral with the chemical formula Sb2S2O. Its color can range from cherry red to a dark red to a black. Kermesite is the result of partial oxidation between stibnite (Sb2S3) and other antimony oxides such as valentinite (Sb2O3) or stibiconite (Sb3O6(OH)). Under certain conditions with oxygenated fluids the transformation of all sulfur to oxygen would occur but kermesite occurs when that transformation is halted.

Chloritoid is a silicate mineral of metamorphic origin. It is an iron magnesium manganese alumino-silicate hydroxide with formula . It occurs as greenish grey to black platy micaceous crystals and foliated masses. Its Mohs hardness is 6.5, unusually high for a platy mineral, and it has a specific gravity of 3.52 to 3.57. It typically occurs in phyllites, schists and marbles.

Okenite (CaSi2O5·2H2O) is a silicate mineral that is usually associated with zeolites. It most commonly is found as small white "cotton ball" formations within basalt geodes. These formations are clusters of straight, radiating, fibrous crystals that are both bendable and fragile. It also belongs to the family of the calcium silicate hydrates (C-S-H) commonly found in hardened cement paste. In cement chemist notation (CCN) it is noted as CaO·2SiO2·2H2O and abbreviated as CS2H2.

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.

Alunogen (from French alun, "alum"), also called feather alum and hair salt is a colourless to white (although often coloured by impurities, such as iron substituting for aluminium) fibrous to needle-like aluminium sulfate mineral. It has the chemical formula Al2(SO4)3·17H2O.

Agrellite () is a rare triclinic inosilicate mineral with four-periodic single chains of silica tetrahedra.

Bustamite is a calcium manganese inosilicate (chain silicate) and a member of the wollastonite group. Magnesium, zinc and iron are common impurities substituting for manganese. Bustamite is the high-temperature polymorph of CaMnSi2O6 and johannsenite is the low temperature polymorph. The inversion takes place at , but may be very slow.Bustamite could be confused with light-colored rhodonite or pyroxmangite, but both these minerals are biaxial (+) whereas bustamite is biaxial (−).

Babingtonite is a calcium iron manganese inosilicate mineral with the formula . It is unusual in that iron(III) completely replaces the aluminium so typical of silicate minerals. It is a very dark green to black translucent (in thin crystals or splinters) mineral crystallizing in the triclinic system with typically radial short prismatic clusters and druzy coatings. It occurs with zeolite minerals in cavities in volcanic rocks. Babingtonite contains both iron(II) and iron(III) and shows weak magnetism. It has a Mohs hardness of 5.5 to 6 and a specific gravity of 3.3.

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.

The mineral anorthoclase ((Na,K)AlSi3O8) is a crystalline solid solution in the alkali feldspar series, in which the proportion of the sodium-aluminium silicate member exceeds the potassium-aluminium silicate member. It typically consists of between 64 and 90 percent of NaAlSi3O8 and between 10 and 36 percent of KAlSi3O8. thumb|left|upright|An anorthoclase crystal from Mount Erebus, Antarctica

Aenigmatite, also known as cossyrite after Cossyra, the ancient name of Pantelleria, is a sodium, iron, titanium inosilicate mineral. The chemical formula is Na2Fe2+5TiSi6O20 and its structure consists of single tetrahedral chains with a repeat unit of four and complex side branches. It forms brown to black triclinic lamellar crystals. It has Mohs hardness of 5.5 to 6 and specific gravity of 3.74 to 3.85. Aenigmatite forms a solid-solution series with wilkinsonite, Na2Fe2+4Fe3+2Si6O20.

Sapphirine is a rare mineral, a silicate of magnesium and aluminium, with the chemical formula ( (with iron as a major impurity). Named for its sapphire-like colour, sapphirine is primarily of interest to researchers and collectors: well-formed crystals are treasured and occasionally cut into gemstones. Sapphirine has also been synthesized for experimental purposes via a hydrothermal process.

Serandite is a mineral with formula Na(Mn2+,Ca)2Si3O8(OH). The mineral was discovered in Guinea in 1931 and named for J. M. Sérand. Serandite is generally red, brown, black or colorless. The correct name lacks an accent.

Pyroxmangite has the general chemical formula of MnSiO3. It is the high-pressure, low-temperature dimorph of rhodonite.

Stilpnomelane is a phyllosilicate mineral. It has the chemical formula .

Amesite is a mineral with general formula of Mg2Al2SiO5(OH)4.

Cuprosklodowskite is a secondary uranium mineral formed by alteration of earlier uranium minerals. Its empirical formula is Cu(UO2)2(HSiO4)2·6(H2O). Cuprosklodowskite is a nesosilicate mineral, It is grass green to dark green in color, and its crystal habit is typically acicular, flat bladed crystals. It is a strongly radioactive mineral.

Gyrolite, NaCa16(Si23Al)O60(OH)8·14H2O, is a rare silicate mineral (basic sodium calcium silicate hydrate: N-C-S-H, in cement chemist notation) belonging to the class of phyllosilicates. Gyrolite is also often associated with zeolites. It is most commonly found as spherical or radial formations in hydrothermally altered basalt and basaltic tuffs. These formations can be glassy, dull or fibrous in appearance.

Pyroxferroite (Fe2+,Ca)SiO3 is a single chain inosilicate. It is mostly composed of iron, silicon and oxygen, with smaller fractions of calcium and several other metals. Together with armalcolite and tranquillityite, it is one of the three minerals which were discovered on the Moon during the 1969 Apollo 11 mission. It was then found in Lunar and Martian meteorites as well as a mineral in the Earth's crust. Pyroxferroite can also be produced by annealing synthetic clinopyroxene at high pressures and temperatures. The mineral is metastable and gradually decomposes at ambient conditions, but thi

Adamsite-(Y) (previously IMA 1999-020), chemical formula NaY(CO3)2·6H2O is a mineral of sodium, yttrium, carbon, oxygen, and hydrogen. It is named after Frank Dawson Adams (1859–1942), professor of geology, McGill University. Its Mohs scale rating is 3.

Johannite is a rare uranium sulfate mineral. It crystallizes in the triclinic crystal system with the chemical composition Cu[UO2(OH)SO4]2·8H2O. It crystallizes in the triclinic system and develops only small prism or thin to thick tabular crystals, usually occurs as flaky or spheroidal aggregates and efflorescent coatings. Its color is emerald-green to apple-green and its streak is pale green.

Ajoite () is a hydrated sodium potassium copper aluminium silicate hydroxide mineral. Ajoite has the chemical formula (Na,K)Cu7AlSi9O24(OH)6·3H2O, and minor Mn, Fe and Ca are usually also present in the structure. Ajoite is used as a minor ore of copper.

Siderotil is an iron(II) sulfate hydrate mineral with formula: FeSO4·5H2O which forms by the dehydration of melanterite. Copper commonly occurs substituting for iron in the structure. It typically occurs as fibrous or powdery encrustations, but may also occur as acicular triclinic crystals.

Vauxite is a phosphate mineral with the chemical formula Fe2+Al2(PO4)2(OH)2·6(H2O). It belongs to the laueite – paravauxite group, paravauxite subgroup, although Mindat puts it as a member of the vantasselite Al4(PO4)3(OH)3·9H2O group. There is no similarity in structure between vauxite and paravauxite Fe2+Al2(PO4)2(OH)2·8H2O or metavauxite Fe3+Al2(PO4)2(OH)2·8H2O, even though they are closely similar chemically and all minerals occur together as secondary minerals. Vauxite was named in 1922 for George Vaux Junior (1863–1927), an American attorney and mineral collector.

Uranopilite is a minor ore of uranium with the chemistry (UO2)6SO4(OH)6O2·14H2O or, hydrated uranyl sulfate hydroxide.

Serendibite is an extremely rare silicate mineral that was first discovered in 1902 in Sri Lanka by Dunil Palitha Gunasekera and named after Serendib, the old Arabic name for Sri Lanka.

Rheniite is a very rare rhenium sulfide mineral with the chemical formula (Rhenium disulfide|). It forms metallic, silver grey platey crystals in the triclinic - pinacoidal class. It has a specific gravity of 7.5.

Alstonite, also known as bromlite, is a low temperature hydrothermal mineral that is a rare double carbonate of calcium and barium with the formula , sometimes with some strontium. Barytocalcite and paralstonite have the same formula but different structures, so these three minerals are said to be trimorphous. Alstonite is triclinic but barytocalcite is monoclinic and paralstonite is trigonal. The species was named Bromlite by Thomas Thomson in 1837 after the Bromley-Hill mine, and alstonite by August Breithaupt of the Freiberg Mining Academy in 1841, after Alston, Cumbria, the base of operati

Bultfonteinite, originally dutoitspanite, is a pink, light-brown or colorless mineral with chemical formula Ca2SiO2(OH,F)4. It was discovered in 1903 or 1904 in the Bultfontein mine in South Africa, for which the mineral is named, and described in 1932.

Lópezite is a rare red chromate mineral with chemical formula: K2Cr2O7. It crystallizes in the triclinic crystal system.

Weloganite is a rare carbonate mineral with the formula: It was discovered by Canadian government mineralogist Ann P. Sabina in 1967 and named for Canadian geologist Sir William Edmond Logan (1798–1875). It was first discovered in Francon Quarry, Montreal, Quebec, Canada and has only been reported from a few localities worldwide.

Schröckingerite is a radioactive yellow uranium-containing carbonate mineral, hydrated sodium calcium uranyl sulfate carbonate fluoride. Schröckingerite crystallizes in the orthorhombic system, occurring as globular clusters, and fluoresces yellow-green under ultraviolet light.

Quenstedtite is an uncommon iron sulfate mineral with chemical formula Fe2(SO4)3·11H2O. It forms violet or white triclinic crystals. Found in oxidized zones of pyrite-rich orebodies, especially in arid climates. It was first reported in 1888 for an occurrence in Tierra Amarilla, Copiapó Province, Atacama Region, Chile and named by G. Linck in 1889 for the German mineralogist F. A. von Quenstedt (1809–1889).

Ussingite is a silicate mineral with formula Na2AlSi3O8(OH).

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. thumb|left|Emmonsite crystal spray from the Moctezuma Mine (3 mm image width) Emmonsite was first described in 1885 for an occurrence in the Tombstone District, Cochise County, Arizona. It was named for the American geologist, Samuel Franklin Emmons, (1841–1911), of the United States Geological Survey.