Trigonal minerals

Leifite is a rare tectosilicate. Tectosilicates are built on a framework of tetrahedra with silicon or aluminium at the centre and oxygen at the vertices; they include feldspars and zeolites, but leifite does not belong in either of these categories. It is a member of the leifite group, which includes telyushenkoite ) and eirikite ). Leifite was discovered in 1915, and named after Leif Ericson who was a Norse explorer who lived around 1000 AD, and was probably the first European to land in North America, nearly 500 years before Christopher Columbus. Eirikite was named in 2007 after Eirik Raude

blue gemstone

Belovite-(Ce) () is the cerium analogue of belovite-(La). It is a member in the belovite group being a subgroup of the apatite group.

Gurimite is a rare mineral with formula Ba3(VO4)2. It is a simple barium vanadate, one of the most simple barium minerals known. It is named after its type locality - Gurim anticline in Israel. It has formed in the rocks of the Hatrurim Formation. Gurimite's stoichiometry is similar to that of copper vanadates mcbirneyite and pseudolyonsite. An example of other barium vanadate mineral is tokyoite.

Chvilevaite (, 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.

Stillwaterite is a palladium arsenide mineral which has a general formula of Pd8As3. Stillwaterite was first discovered in the Banded and Upper zones of the Stillwater igneous complex in Montana, United States, and has been reported in the Lac-des-Iles area of Ontario, Canada. Outside of North America, this rare mineral has been found in northern Finland.

Shandite is a sulfide mineral with chemical formula: Ni3Pb2S2. It was discovered in 1948 by the German mineralogist Paul Raumdohr who named it named after Scottish petrologist, Samuel James Shand (1882–1957). Ramdohr characterized shandite by its metallic luster and a brass-yellow color. It has a specific gravity of 8.92, and a Mohs hardness value of 4. Shandite is commonly found as an inclusion in other minerals such as Heazelwoodite Ni3S2 or serpentine.

Raslakite is a rare mineral of the eudialyte group with the chemical formula . This formula is based on the original one, and is extended to show the presence of cyclic silicate groups. The additional silicon and oxygen shown in separation from the cyclic groups (in parentheses) are in fact connected with two 9-fold rings. The mineral has lowered symmetry (space group R3, instead of more specific for the group R3m one), similarly to some other eudialyte-group members: aqualite, labyrinthite, oneillite and voronkovite. The specific feature of raslakite is, among others, the presence of sodium a

Aqualite is a very rare mineral of the eudialyte group, with formula (H3O)8(Na,K,Sr)5Ca6Zr3SiSi(Si24O66)(OH)9Cl. The formula given does not show the presence of cyclic silicate groups. The original formula was extended to show the presence of silicon at both M3 and M4 sites, according to the nomenclature of the eudialyte group. Aqualite is unique among the eudialyte group in being hydronium-rich (the only other eudialyte-group species with essential hydronium, is the recently discovered ilyukhinite). Among the other representatives of the group it also distinguish in splitting of the M1 site i

Lucchesiite is a new member of tourmaline-group of minerals. Lucchesiite has the formula CaFe3Al6(Si6O18)(BO3)3(OH)3O. It is the calcium and oxygen-analogue of schorl. It has two co-type localizations, one in Czech Republic and the other in Sri Lanka. As the other members of the tourmaline group, it is trigonal.

Changbaiite (PbNb2O6) is a member of the oxide mineral class in which the mineral contains oxygen which is grouped along with one or two metal ion. Changbaiite is classified as a multiple Oxide XY2O6 and it generally has an ionic bond. Furthermore, it is also orthorhombic at a temperature of 25 °C and it changes to orthorhombic-tetragonal at 570 °C.

Ikranite is a member of the eudialyte group, named after the Shubinov Institute of Crystallography of the Russian Academy of Sciences. It is a cyclosilicate mineral that shows trigonal symmetry with the space group R3m, and is often seen with a pseudo-hexagonal habit. Ikranite appears as translucent and ranges in color from yellow to a brownish yellow. This mineral ranks a 5 on Mohs scale of mineral hardness, though it is considered brittle, exhibiting conchoidal fracture when broken.

Fluor-liddicoatite is a rare member of the tourmaline group of minerals, elbaite subgroup, and the theoretical calcium endmember of the elbaite-fluor-liddicoatite series; the pure end-member has not yet been found in nature. Fluor-liddicoatite is indistinguishable from elbaite by X-ray diffraction techniques. It forms a series with elbaite and probably also with olenite. Liddiocoatite is currently a non-approved mineral name, but Aurisicchio et al. (1999) and Breaks et al. (2008) found OH-dominant species. Formulae are Fluor-liddicoatite Ca(Li2Al)Al6(BO3)3Si6O18(OH)3F Elbaite Na(Al1.5Li1.5)A

Charlesite is a sulfate mineral of the ettringite group. Charlesite was named in 1945 after Dr. Charles Palache, a mineralogist and professor at Harvard University for his work on minerals. This mineral is extremely rare, and when it is found it is usually in crystal (but not gem) form. Its crystals are soft and hexagonal, and can vary in color. Colors can range from clear to white, or even pale yellow or pink. The brittle mineral's Mohs hardness is 2.5 with a specific gravity of 1.79. Though transparent to the eye, the mineral has a white streak.

Khomyakovite is an exceedingly rare mineral of the eudialyte group, with formula . The original formula was extended to show the presence of both the cyclic silicate groups and M4-site silicon, according to the nomenclature of the eudialyte group. Some niobium substitutes for tungsten in khomyakovite. Khomyakovite is an iron-analogue of manganokhomyakovite, the second mineral being a bit more common. The two minerals are the only group representatives, beside taseqite, with species-defining strontium, although many other members display strontium diadochy. Khomyakovite is the third eudialyte-g

Loveringite is a rare metallic oxide mineral of the crichtonite group with the chemical formula . It is a late-stage magmatic mineral, formed in the residual melt of mafic layered intrusions in either the olivine-chromite, pyroxene, or plagioclase-rich layers.

Amakinite (IMA symbol: Amk) is a semi transparent yellow-green hydroxide mineral belonging to the brucite group that was discovered in 1962. Its chemical formula is written as (Fe2+,Mg)(OH)2. It usually occurs in the form of splotchy, anhedral crystals forming within a group or structure in other minerals or rocks, such as kimberlite (occurring in diamond-rich eruptive pipe). Its composition is as follows:

Combeite is a rare silicate mineral with the formula Na2Ca2Si3O9. It has a trigonal crystal system.

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

Merenskyite is a rare telluride / bismuthinide mineral with the chemical formula . It is an opaque white to light gray metallic mineral that occurs as inclusions within other minerals such as chalcopyrite. It crystallizes in the trigonal crystal system.

Kosnarite is an alkali zirconium phosphate mineral (KZr2(PO4)3) named after an expert of pegmatites Richard Andrew "Rich" Kosnar, well-known mineral dealer and collector from Colorado (November 13, 1946 - January 15, 2007). Kosnarite contains potassium, oxygen, phosphorus, and zirconium with sodium, rubidium, hafnium, manganese and fluorine (Na, Rb, Hf, Mn, and F) being common impurities found in kosnarite. It was discovered in nature for the first time in 1991 by Vandall T. King. Samples that were found in granitic pegmatites from the Mount Mica Quarry, Paris, Oxford County, Maine, US were se

Taranakite is a hydrated alkali iron-aluminium phosphate mineral with the chemical formula .

Zirsilite-(Ce) is a very rare mineral of the eudialyte group, with formula . The original formula was extended to show the presence of cyclic silicate groups and the presence of silicon at the M4 site, according to the nomenclature of the eudialyte group. Zirsilite-(Ce) differs from carbokentbrooksite in cerium-dominance over sodium only. Both minerals are intimately associated. The only other currently known representative of the eudialyte group having rare earth elements (in particular cerium, as suggested by the "-Ce)" Levinson suffix in the name) in dominance is johnsenite-(Ce).

Motukoreaite is a mineral with formula Mg6Al3(OH)18[Na(H2O)6](SO4)2·6H2O (possibly more than one species). The mineral is named for Motukorea, the island in New Zealand where it was discovered. Motukoreaite was first noted in 1941 and officially described in 1977.

Tancaite-(Ce) is a very rare molybdate mineral with the formula FeCe(MoO4)3•3H2O. It was found in Punta de Su Seinargiu locality on Sardinia, Italy. Red crystals of tancaite-(Ce) resemble modified cubes, but the mineral is trigonal (space group R-3). The type locality of tancaite-(Ce) is also a place of discovery of other molybdate minerals, including thorium molybdates ichnusaite and nuragheite.

Ungemachite is a rare mineral (K3Na8Fe(SO4)6(NO3)2 · 6H2O) known from only two locations - a copper deposit in the Atacama Desert (Chile) and in the New Cobar copper–gold deposit, New South Wales (Australia). The formation of Ungemachite requires the presence of nitrate minerals, which requires arid conditions, as well as sulfates. It has been synthesized under laboratory conditions and its properties have been studied. The mineral was described in 1936 and is named after the mineralogist Henri Ungemach.

Satterlyite is a hydroxyl bearing iron phosphate mineral. The mineral can be found in phosphatic shales and was first discovered in the Big Fish River area in Yukon Territory, Canada.

Gordaite is a sulfate mineral composed primarily of hydrous zinc sodium sulfate chloride hydroxide with formula: NaZn4(SO4)(OH)6Cl·6H2O. It was named for the discovery location in the Sierra Gorda district of Chile. Gordaite forms as tabular trigonal crystals.

Perhamite is a phosphate mineral with the formula Ca3Al7(SiO4)3(PO4)4(OH)3·16.5(H2O). It occurs in rare isolated masses in amblygonite-rich pegmatite deposits throughout the world. It was discovered in platy sheed form of 1mm hexagonal crystals. It was first described in 1977 by P.J. Dunn and D.E. Appleman from pegmatite collected from Bell Pit, Newry, Maine. Other specimens have been found in Kapunda, South Australia, in Silver Coin mine near Humboldt County, Nevada and various locations throughout Europe.

Alluaivite is a rare mineral of the eudialyte group, with complex formula written as . It is unique among the eudialyte group as the only titanosilicate (other representatives of the group are usually zirconosilicates). The two dual-nature minerals of the group, being both titano- and zirconosilicates, are labyrinthite and dualite. They both contain alluaivite module in their structures. Alluaivite is named after Mt. Alluaiv in Lovozero Tundry massif, Kola Peninsula, Russia, where it is found in ultra-agpaitic, hyperalkaline pegmatites.

Allendeite, Sc4Zr3O12, is an oxide mineral. Allendeite was discovered in a small ultrarefractory inclusion within the Allende meteorite. This inclusion has been named ACM-1. It is one of several scandium rich minerals that have been found in meteorites. Allendeite is trigonal, with a calculated density of 4.84 g/cm3. The new mineral was found along with hexamolybdenum. These minerals, are believed to demonstrate conditions during the early stages of the Solar System, as is the case with many CV3 carbonaceous chondrites such as the Allende meteorite. It is named after the Allende meteorite

thumb | 220x124px | right | alt= SEM BSE images showing kaitianite (Ktn) with tistarite (Tta), Ti,Al,Zr-oxide (TAZ), MgTi3+2Al4SiO12 phase (MTAS), spinel (Spl), sapphirine (Spr), and Ti-sulfide (Ti-S) in corundum Grain 1125C2. The upper rectangular area in (b) are enlarged in (c) | SEM BSE images showing kaitianite (Ktn) with tistarite (Tta), Ti,Al,Zr-oxide (TAZ), MgTi3+2Al4SiO12 phase (MTAS), spinel (Spl), sapphirine (Spr), and Ti-sulfide (Ti-S) in corundum Grain 1125C2. The upper rectangular area in (b) are enlarged in (c) Tistarite is an exceedingly rare mineral with the formula Ti2O3, thus

Belovite-(La) () is the lanthanum analogue of belovite-(Ce). It is a member in the belovite group being a subgroup of the apatite group.

Jaffeite is a hydrated calcium silicate with the following chemical formula:

Geerite is a copper sulfide mineral with the chemical formula Cu8S5. The mineral is named after the original collector, Adam Geer, of Utica, New York, US.

Ximengite is a phosphate mineral discovered in and named for the Ximeng tin-mining district in China. Chemically, it is bismuth phosphate.

thumb | right Takedaite is a borate mineral that was found in a mine in Fuka, Okayama Prefecture Japan during a mineralogical survey in the year 1994. During the survey, Kusachi and Henmi reported the occurrence of an unidentified anhydrous borate mineral closely associated with nifontovite, olshanskyite, and calcite. By the year 1994 two other minerals in the borate group M3B2O6 had been identified in nature Mg3B2O6 known as kotoite and Mn3B2O6 known as jimboite. Takedaite has the ideal chemical formula of Ca3B2O6. The mineral has been approved by the Commission on New Minerals and Mineral Na

Mesitite (from — middle, between), formerly better known as mesitine spar, ferrous magnesite or brown spar is a variety of magnesite, a carbonate mineral, one of the so-called brown spars, regarded as an iron-bearing variety of magnesite or, in other cases, breunnerite. True to its name, mesitite is the middle member of a continuous isomorphic series magnesite—siderite with the general formula (Mg,Fe)CO3, in which the iron ion content (Fe2+) is approximately 30 to 50%, and the iron to magnesium ratio ranges, accordingly, from 30:70 to 50:50.

Fengchengite is a rare mineral of the eudialyte group with the formula . The formula is simplified as it does not show the presence of cyclic silicate groups. When compared to other minerals of the group, fengchengite characterizes in the presence of ferric iron (thus similar to ikranite, mogovidite and feklichevite) and essential, site-dominating vacancies. The mineral was discovered in the Saima complex near Fengcheng city in China – hence its name.

Ferronigerite-2N1S is an iron, tin, alumino-hydroxide mineral that naturally occurs around sillimanite-quartz veins. Ferronigerite-2N1S belongs to the nigerite group, högbomite supergroup. The other constituents of the nigerite group are ferronigerite-6N6S, magnesionigerite-2N1S, magnesionigerite-6N6S, zinconigerite-2N1S and zinconigerite-6N6S. The 2N1S ending stands for the nolanite and spinel structural layers.

Davinciite is a very rare mineral of the eudialyte group, with the simplified formula Na12K3Ca6Fe32+Zr3(Si26O73OH)Cl2. The formula given does not show the presence of cyclic silicate groups. The mineral was named after Leonardo da Vinci to refer to the atypical geometrical forms he tended to use, compared by the authors of the mineral description to the atypical (not ideally centrosymmetrical) geometry of the Davinciite structure. The other quite atypical feature of Davinciite is its lavender colour, while the typical eudialyte is rather pink or red.

Andrianovite is a very rare mineral of the eudialyte group, with formula Na12(K,Sr,Ce)6Ca6(Mn,Fe)3Zr3NbSi(Si3O9)2(Si9O27)2O(O,H2O,OH)5. The original formula was extended to show the presence of cyclic silicate groups and silicon at the M4 site, according to the nomenclature of eudialyte group. Andrianovite is unique among the eudialyte group in being potassium-rich (other eudialyte-group species with essential K are davinciite and rastsvetaevite). It is regarded as potassium analogue of kentbrooksite, but it also differs from it in being oxygen-dominant rather than fluorine-dominant. Also, the

Zussmanite is a hydrated iron-rich silicate mineral with the chemical formula . It occurs as pale green crystals with perfect cleavage.

Kentbrooksite is a moderately rare mineral of the eudialyte group, with chemical formula . This extended formula shows the presence of cyclic silicate groups and dominance of Si at the M4 site, according to the nomenclature of the eudialyte group. The characteristic features of kentbrooksite, that make it different from eudialyte are: (1) dominancy of fluorine (the only currently known example among the whole group), (2) dominancy of manganese, and (3) dominancy of niobium. Trace hafnium and magnesium are also reported. Kentbrooksite is relatively common when compared to most other species of

Ferrokentbrooksite is a moderately rare mineral of the eudialyte group, with formula . The original formula was extended form to show the presence of cyclic silicate groups and presence of silicon at the M4 site, according to the nomenclature of eudialyte group. As suggested by its name, it is the (ferrous) iron analogue of kentbrooksite. When compared to the latter, it is also chlorine-dominant instead of being fluorine-dominant. The original (holotype) material is also relatively enriched in rare earth elements, including cerium and yttrium.

Yoshiokaite, a mineral formed as shocked crystal fragments in devitrified glass, was discovered in lunar regolith breccia collected from a trench by the Apollo 14 crew in 1971. Although there have been other minerals (armalcolite and tranquillityite) that have been originally discovered on the Moon, yoshiokaite is the first new mineral with origin related to lunar highlands. Yoshiokaite is considered to be a member of the feldspathoid group.

Rastsveatevite is a rare mineral of the eudialyte group with the chemical formula . Its structure is modular. It is only the third member of the group after andrianovite and davinciite with essential (site-dominating) potassium. Potassium and sodium enter both N4 and M2 sites. The mineral is named after Russian crystallographer Ramiza K. Rastsvetaeva.

Florencite-(Sm) is a very rare mineral of the plumbogummite group (alunite supergroup) with simplified formula SmAl3(PO4)2(OH)6. Samarium in florencite-(Sm) is substituted by other rare earth elements, mostly neodymium. It does not form separate crystals, but is found as zones in florencite-(Ce), which is cerium-dominant member of the plumbogummite group. Florencite-(Sm) is also a samarium-analogue of florencite-(La) (lanthanum-dominant) and waylandite (bismuth-dominant), both being aluminium-rich minerals.

Waylandite is the phosphate analogue of arsenowaylandite and the aluminum analogue of zaïrite. The mineral was approved by the IMA in 1962, and was published the same year. Waylandite was named in honor of Edgar James Wayland. It is a member of the alunite supergroup, and a member of the plumbogummite – also known as crandallite – group. So far, only two bismuth-bearing members of the alunite supergroup are known, one of which is waylandite, alongside its ferric iron analogue zaïrite.

Georgbarsanovite is a very rare mineral of the eudialyte group, formerly known under unaccepted name as barsanovite, with formula . The original formula was extended to show the presence of cyclic silicate groups and the domination of silicon at the M4 site. "REE", standing for rare earth elements, is dominated by cerium. Georgbarsanovite is characterized in dominance of manganese at the N4 site. It also differs from most other accepted group representatives in its colour. The mineral was found in nepheline pegmatite near Petrelius River, Khibiny massif, Kola Peninsula, Russia. It is named aft

Carlosruizite is a sulfate or selenate–iodate mineral with chemical formula: K6(Na,K)4Na6Mg10(SeO4)12(IO3)12·12H2O. It has a low density (specific gravity of 3.36), colorless to pale yellow, transparent mineral which crystallizes in the trigonal crystal system. It forms a series with fuenzalidaite.

Feklichevite is a rare mineral of the eudialyte group with the formula Na11Ca9(Fe3+,Fe2+)2Zr3NbSi(Si3O9)2(Si9O27)2. The original formula was extended to show the presence of cyclic silicate groups and presence of silicon at the M4 site, according to the nomenclature of eudialyte group. When compared to other minerals of the group, feklichevite characterizes in the presence of ferric iron (thus similar to ikranite, mogovidite and fengchengite) and dominance of calcium at the N4 site. Calcium is ordered in the structure and is also present at the M1 site. Other iron-bearing minerals of the group

Dessauite-(Y) is a mineral member of the crichtonite group with the formula . It is associated with derbylite, hematite, rutile, karelianite, siderite, and calcite. Founded in the Buca della Vena Mine, Tuscany, Italy, the mineral was called dessauite in honor of professor Gabor Dessau (1907–1983).

Cervandonite is a rare arsenosilicate mineral. It has a chemical formula or . It has a monoclinic crustal structure with supercell (Z=6), the crystal structure was established as a trigonal subcell, with space group R3m and a = 6.508(1)Ǻ, c = 18.520(3) Ǻ, V 679.4(2) Ǻ3, and Z=3. It was first described by Buhler Armbruster in 1988, but it has proven to be problem due to the extreme scarcity of single crystals and its unusual replacement of silicon and arsenic. Cervandonite is named after the location where it was first described, Pizzo Cervandone (Scherbadung), Italy in the Central Alps.

Sabelliite is a mineral that was first discovered at the Is Murvonis Mine in Dosmusnovas, Sardinia. It was discovered growing in an old fluorite mine. It grows as an inter-grown aggregate or as an isolated crystal in a compact quartzitic matrix. It appears as a platy disc-shaped emerald green transparent crystal. The mineral was named after Dr. Cesare Sabelli, researcher at the Consiglio Nazionale delle Ricerche. Sabelliite's ideal chemical formula is (Cu,Zn)2Zn[(As,Sb)O4](OH)3

Dualite is a very rare and complex mineral of the eudialyte group, its complexity being expressed in its formula . The formula is simplified as it does not show the presence of cyclic silicate groups. The name of the mineral comes from its dual nature: zircono- and titanosilicate at once. Dualite has two modules in its structure: alluaivite one and eudialyte one. After alluaivite and labyrinthite it stands for third representative of the eudialyte group with essential titanium.

Manganoeudialyte is an moderately rare mineral of the eudialyte group, with formula Na14Ca6Mn3Zr3Si2[Si24O72(OH)2]Cl2·4H2O. The formula given is one of the forms that can be given, based on the originally reported one, and shows dominance of silicon at both the M3 and M4 sites. As suggested by its name, it is the manganese-analogue of eudialyte.

Sabieite is a mineral with the chemical formula (NH4)Fe3+(SO4)2. Its type locality is Lone Creek Falls cave, Sabie, Pilgrim's Rest District Ehlanzeni, Mpumalanga Province, South Africa. Its crystals are trigonal to trapezohedral. It is white and leaves a white streak. It is transparent and has an earthy luster. Sabieite is rated 2 on the Mohs Scale.

Zadovite is an extremely rare mineral with formula BaCa6[(SiO4)(PO4)](PO4)2F. Together with its vanadium-analogue, aradite, zadovite occur in paralavas (type of pyrometamorphic rocks). Both minerals have structures similar to nabimusaite, and these three minerals occur in the Hatrurim Formation of Israel. Structure of all three minerals is related to that of hatrurite. Minerals combining barium, phosphorus and silicon together are scarce.

Aradite is a very rare mineral with formula BaCa6[(SiO4)(VO4)](VO4)2F. Aradite and its phosphorus-analogue, zadovite, were found in paralavas (rocks formed due to pyrometamorphism) of the Hatrurim Formation. Both aradite and zadovite have structures similar to that of nabimusaite. Structure of all three minerals is related to that of hatrurite.