Hexagonal minerals

Paratacamite is a mineral in the halide minerals category. Its chemical formula is . Its name is derived from its association with atacamite. Paratacamite was first described by Herbert Smith in 1906. The zincian endmember is called herbertsmithite, and paratacamite is polymorphous with botallackite and atacamite.

thumb | right | White vitreous crystal aggregates of the extremely rare Al mineral akdalaite from the TL (Solnechnoye Mine, Kara-Oba, Karazhal, Ulytau Region, Kazakhstan) and only one of 6 known localities worldwide. Ex Vandenbroucke Museum collection from Waregem, Belgium. Akdalaite (IMA symbol: Akd) is a very rare mineral found in Kazakhstan and has the formula . It was formerly believed to be . It is therefore the same as tohdite an artificially produced phase. Studies on the crystal structure and spectra indicate that this is an aluminium oxide hydroxide.

Rambergite is a manganese sulfide mineral with formula .

Cadmoselite is a rare cadmium selenide mineral with chemical formula CdSe. Cadmoselite crystallizes in the hexagonal system and occurs as black to pale grey opaque crystals and grains.

Haggertyite is a rare barium, iron, magnesium, titanate mineral: Ba(Fe2+6Ti5Mg)O19 first described in 1996 from the Crater of Diamonds State Park near Murfreesboro in Pike County, Arkansas. The microscopic metallic mineral crystallizes in the hexagonal system and forms tiny hexagonal plates associated with richterite and serpentinitized olivine of mafic xenoliths in the lamproite host rock. It is an iron(II) rich member of the magnetoplumbite group. It is a light grey opaque mineral with calculated Mohs hardness of 5.

Gregoryite is an anhydrous carbonate mineral that is rich in potassium and sodium with the chemical formula . It is one of the two main ingredients of natrocarbonatite, found naturally in the lava of Ol Doinyo Lengai volcano of Arusha Region, Tanzania, and the other being nyerereite.

Brockite is a rare earth phosphate mineral with formula: . It crystallizes in the hexagonal system in the chiral space group 180 or its enantiomorph 181. It is typically granular to massive with only rare occurrence of stubby crystals. It is radioactive due to the thorium content.

Agardite is a mineral group consisting of agardite-(Y), agardite-(Ce), agardite-(Nd), and agardite-(La). They comprise a group of minerals that are hydrous hydrated arsenates of rare-earth elements (REE) and copper, with the general chemical formula (REE,Ca)Cu6(AsO4)3(OH)6·3H2O. Yttrium, cerium, neodymium, lanthanum, as well as trace to minor amounts of other REEs, are present in their structure. Agardite-(Y) is probably the most often found representative. They form needle-like yellow-green (variably hued) crystals in the hexagonal crystal system. Agardite minerals are a member of the mixite

Fluoborite has a chemical formula of Mg3(BO3)(F,OH)3. Its name comes from its main chemical components, fluorine and boron. It was first described in 1926.

Drysdallite is a rare molybdenum selenium sulfide mineral with formula Mo(Se,S)2. It crystallizes in the hexagonal system as small pyramidal crystals or in cleavable masses. It is an opaque metallic mineral with a Mohs hardness of 1 to 1.5 and a specific gravity of 6.25. Like molybdenite it is pliable with perfect cleavage.

Kambaldaite, NaNi4(CO3)3(OH)3·3H2O, is an extremely rare hydrated sodium nickel carbonate mineral described from gossaniferous material associated with Kambalda type komatiitic nickel ore deposits at Kambalda, Western Australia, and Widgie Townsite nickel gossan, Widgiemooltha, Western Australia.

thumb | right Atheneite is a rare palladium, mercury arsenide mineral with the chemical formula associated with palladium–gold deposits. Its composition parallels that of arsenopalladinite (), isomertieite () and meritieite-II () (Cabral, 2002).

Fluorcaphite is a mineral with the chemical formula . It is found in the Kola Peninsula in Russia. Its crystals are hexagonal (dipyramidal class) and are transparent with a vitreous luster. It is light to bright yellow, leaves a white streak and is rated five on the Mohs Scale. Fluorcaphite is radioactive.

Zaccagnaite is a mineral, with a formula Zn4Al2CO3(OH)12·3H2O. It occurs as white hexagonal crystals associated with calcite in cavites in Carrara marble of the Italian Alps and is thought to have formed by hydrothermal alteration of sphalerite in an aluminium rich environment. It is named after Domenico Zaccagna (1851–1940), an Italian mineral collector.

Yagiite is a cyclosilicate mineral belonging to the osumilite group. It was discovered in 1968 in the iron meteorite that fell in Colomera in the province of Granada (Spain). Named after the Japanese mineralogist Kenzo Yagi, its CAS Registry Number is IMA1968-020.

Kamiokite is an iron-molybdenum oxide mineral with the chemical formula Fe2Mo3O8. The name kamiokite is derived from the locality, the Kamioka mine in Gifu Prefecture, Japan, where this mineral was first discovered in 1975.

Weissite is a telluride mineral, a copper telluride. Its chemical formula is . Weissite has hexagonal crystal structure. Its specific gravity is 6 and its Mohs hardness is 3. Occurrence is in Gunnison County, Colorado, Arizona and New Mexico in the United States. It is also reported from Kalgoorlie, Western Australia and Dalarna and Värmland, Sweden.

Xifengite (Fe5Si3) is a rare metallic iron silicide mineral. The crystal system of xifengite is hexagonal. It has a specific gravity of 6.45 and a Mohs hardness of 5.5. It occurs as steel gray inclusions within other meteorite derived nickel iron mineral phases.

Johnbaumite is a calcium arsenate hydroxide mineral. It was first described in 1980, where it appeared in Franklin, Sussex County, New Jersey. Johnbaumite was discovered at Harstigen mine in Sweden in the 19th century, but it was described as svabite.

Grayite, ThPO4·(H2O), is a thorium phosphate mineral of the Rabdophane group first discovered in 1957 by S.H.U. Bowie in Rhodesia. It is of moderate hardness occurring occasionally in aggregates of hexagonal crystals occasionally but more commonly in microgranular/cryptocrystalline masses. Due to its thorium content, grayite displays some radioactivity although it is only moderate and the mineral displays powder XRD peaks without any metamict-like effects. The color of grayite is most commonly observed as a light to dark reddish brown but has also been observed as lighter yellows with grayish

Jamborite is a hexagonal-trigonal, green, mineral consisting of nickel, cobalt, hydroxides and sulphur. Its discovery was first published in 1973.

Cesanite is the end member of the apatite-wilkeite-ellestadite series that substitutes all of apatite's phosphate ions with sulfate ions and balances the difference in charge by replacing several calcium ions with sodium ions. Currently very few sites bearing cesanite have been found and are limited to a geothermal field in Cesano, Italy from which its name is derived, Măgurici Cave in Romania, and in the San Salvador Island caves in the Bahamas.

Fluorellestadite is a rare nesosilicate of calcium, with sulfate and fluorine, with the chemical formula Ca10(SiO4)3(SO4)3F2. It is a member of the apatite group, and forms a series with hydroxylellestadite.

Qusongite is an extremely rare mineral with the simple formula WC, which shows the mineral to be a naturally occurring tungsten carbide. It was found in Luobusa ophiolite, China. This ophiolite is known for many natural reduced compounds, including native metals, diamond, silicides and carbides (e.g., moissanite, natural silicon carbide). Qusongite crystallizes in the hexagonal system, with space group P-6m2.

Aliettite is a complex phyllosilicate mineral of the smectite group with a formula of (Ca0.2Mg6(Si,Al)8O20(OH)4·4H2O) or .

Tienshanite, named for the Tian Shan Range in Mongolia, is a rare borosilicate mineral, though rock-forming in some parts of its original locality at the Dara-i-Pioz Glacier in Tajikistan. Its formula is extremely complex: .

Pabstite is a barium tin titanium silicate mineral that is found in contact metamorphosed limestone. It belongs to the benitoite group of minerals. The chemical formula of pabstite is . It is found in Santa Cruz, California. The crystal system of the mineral is hexagonal.

Genplesite is a very rare tin mineral coming from the Oktyabr'skoe deposit in the Noril'sk area, Russia, which is known for nickel and platinum group elements minerals. Its chemical formula is Ca3Sn(SO4)2(OH)6•3H2O. Genplesite is a member of the fleischerite group, and it is a calcium and tin-analogue of fleischerite. It is hexagonal, with space group P63/mmc.

Lucabindiite is a mineral discovered in 1998 from the La Fossa crater at Vulcano, the Aeolian islands off the coast of Italy. It has the chemical formula ( and is hexagonal. After months of collecting sublimates and encrustations, the researchers discovered lucabindiite which was found on the surface of pyroclastic breccia. The mineral is named after Luca Bindi, who was a professor of mineralogy and former head of the Division of Mineralogy of the Natural History Museum of the University of Florence.

Hexamolybdenum is a molybdenum dominant alloy discovered during a nanomineralogy investigation of the Allende meteorite. Hexamolybdenum was discovered in a small ultrarefractory inclusion within the Allende meteorite. This inclusion has been named ACM-1. Hexamolybdenum is hexagonal, with a calculated density of 11.90 g/cm3. The new mineral was found along with allendeite. 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. Hexamolybdenum lies on a continuum o

Klöchite is a cyclosilicate mineral of the Osumilite Group, found in a basalt quarry in Klöch, Austria. The basalt quarry it was found in is part of the Styrian Basin Volcanic Field in south-eastern Austria. Klöchite was found to be hosted in a xenolith primarily composed of quartz, sanidine, and diopside. Very few vesicles in the xenolith held Klöchite crystals, and only two samples were taken for study.

Pimelite was discredited as a mineral species by the International Mineralogical Association (IMA) in 2006, in an article which suggests that "pimelite" specimens are probably willemseite (which is approved), or kerolite (which is also discredited). This was a mass discreditation, and not based on any re-examination of the type material (assuming any exists). Nevertheless, a considerable number of papers have been written, verifying that pimelite is a nickel-dominant smectite. It is always possible to redefine a mineral wrongly discredited.

Reederite-(Y) is a rare mineral with the formula . It is the only known mineral with fluorosulfate (fluorosulfonate). "REE" in the formula stands for rare earth elements other than yttrium, that is mostly cerium, with traces of neodymium, dysprosium, lanthanum and erbium. The formula also includes a Levinson suffix "-(Y)" pointing to the dominance of yttrium at the corresponding site. Reederite-(Y) crystallizes in the hexagonal crystal system with the space group P, rarely seen among minerals.