Tourmaline is a crystalline boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. This gemstone can be found in a wide variety of colors.
Actinolite is an amphibole silicate mineral with the chemical formula Ca2(Mg4.5-2.5Fe2+0.5-2.5)Si8O22(OH)2.
Axinite is a brown to violet-brown, or reddish-brown bladed group of minerals composed of calcium aluminium boro-silicate, (Ca,Fe,Mn)3Al2BO3Si4O12OH. Axinite is pyroelectric and piezoelectric.
Elbaite, a sodium, lithium, aluminium boro-silicate, with the chemical composition Na(Li1.5Al1.5)Al6Si6O18(BO3)3(OH)4, is a mineral species belonging to the six-member ring cyclosilicate tourmaline group.
Cerite is a complex silicate mineral group containing cerium, formula (Ce,La,Ca)
9(Mg,Fe3+
)(SiO
4)
6(SiO
3OH)(OH)
3. The cerium and lanthanum content varies with the Ce rich species and the La rich species. Analysis of a sample from the Mountain Pass carbonatite gave 35.05% Ce
2O
3 and 30.04% La
2O
3.
Clinozoisite is a complex calcium aluminium sorosilicate mineral with formula: Ca2Al3(Si2O7)(SiO4)O(OH). It forms a continuous solid solution series with epidote by substitution of iron(III) in the aluminium (m3 site) and is also called aluminium epidote.
Calderite is a mineral in the garnet group with the chemical formula (Mn2+, Ca)3(Fe3+, Al)2(SiO4)3.
Kornerupine (also called Prismatine) is a rare boro-silicate mineral with the chemical formula (Mg,Fe2+)4(Al,Fe3+)6(SiO4,BO4)5(O,OH)2. It crystallizes in the orthorhombic - dipyramidal crystal system as brown, green, yellow to colorless slender tourmaline like prisms or in massive fibrous forms. It has a Mohs hardness of 7 and a specific gravity of 3.3 to 3.34. Its indices of refraction are nα=1.660 - 1.671, nβ=1.673 - 1.683 and nγ=1.674 - 1.684.
Aliettite is a complex phyllosilicate mineral of the smectite group with a formula of (Ca0.2Mg6(Si,Al)8O20(OH)4·4H2O) or [Mg3Si4O10(OH)2](Ca0.5,Na)0.33(Al,Mg,Fe2+)2–3(Si,Al)4O10(OH)2·n(H2O).
Fluor-buergerite, originally named buergerite, is a mineral species belonging to the tourmaline group. It was first described for an occurrence in rhyolitic cavities near Mexquitic, San Luis Potosi, Mexico. It was approved as a mineral in 1966 by the IMA and named in honor of Martin J. Buerger (1903–1986), professor of mineralogy at the Massachusetts Institute of Technology. It has also been reported from Minas Gerais, Brazil, and the Central Bohemia Region of the Czech Republic.
Gedrite is a crystal belonging to the orthorhombic ferromagnesian subgroup of the amphibole supergroup of the double chain inosilicate minerals with the ideal chemical formula Mg2(Mg3Al2)(Si6Al2)O22(OH)2.
Alluaivite is a rare mineral of the eudialyte group, with complex formula written as Na19(Ca,Mn)6(Ti,Nb)3Si26O74Cl·2H2O. 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.
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-uvite is a tourmaline mineral with the chemical formula CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3F. It is a rare mineral that is found in calcium rich contact metamorphic rocks with increased amounts of boron. Uvite is trigonal hexagonal, which means that it has three equal length axes at 120 degrees, all perpendicular to its fourth axis which has a different length. Uvite is part of the space group 3m. Uvite's hardness has been measured to be 7.5 on the Mohs hardness scale. The color of uvite widely varies, depending on the sample, but is mostly deep green or brown. In regard to uvite's optical properties, it is uniaxial (-) and anisotropic, meaning that the velocity of light in the mineral depends on the path that it takes. In plane polarized light, uvite is colorless to pale yellow and shows weak pleochroism.
Fengchengite is a rare mineral of the eudialyte group with the formula Na12[ ]3(Ca,Sr)6Fe33+Zr3Si(Si25O73)(H2O,OH)3(OH,Cl)2. 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 and essential, site-dominating vacancies. The mineral was discovered in the Saima complex near Fengcheng city in China - hence its name.
Golyshevite is a rare mineral of the eudialyte group, with formula Na10Ca3Ca6Zr3Fe2SiNb(Si3O9)2(Si9O27)2CO3(OH)3•H2O. The original formula was extended to show both the presence of cyclic silicate groups and silicon at the M4 site, according to the nomenclature of the eudialyte group. The characteristic feature of golyshevite is calcium-rich composition, with calcium at two main sites instead of one site. Together with feklichevite, fengchengite, ikranite and mogovidite it is a ferric-iron-dominant representative of the group. It is chemically similar to mogovidite. Golyshevite was named after Russian crystallographer Vladimir Mikhailovich Golyshev.
Fluorcarmoite-(BaNa) is a rare phosphate mineral, belonging to arrojadite group, with the formula Ba[]Na2Na2[]CaMg13Al(PO4)11(PO3OH)F2. It is a barium-rich member of the group, as is arrojadite-(BaNa), arrojadite-(BaFe), fluorarrojadite-(BaFe) and an unapproved species ferri-arrojadite-(BaNa). The "-(BaNa)" suffix informs about the dominance of the particular elements (here barium and sodium) at the corresponding structural sites.
Manganiceladonite is a rare silicate mineral with the formula KMgMn3+Si4O10(OH)2. It is one of many minerals discovered in the Cerchiara mine, La Spezia, Liguria, Italy.
Ferro-ferri-hornblende is an amphibole-supergroup mineral with the formula ☐Ca2(Fe2+4Fe3+)(Si7Al)O22(OH)2. It contains essential vacancy (☐). It was discovered in the Traversella mine, Canavese, Torino, Piedmont, Italy.
