Titanite, or sphene (from the Greek sphenos (σφηνώ), meaning wedge), is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are typically present. Also commonly present are rare earth metals including cerium and yttrium; calcium may be partly replaced by thorium.
Goethite is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the "α" polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient times for its use as a pigment. Evidence has been found of its use in paint pigment samples taken from the caves of Lascaux in France. It was first described in 1806 based on samples found in the Hollertszug Mine in Herdorf, Germany. The mineral was named after the German polymath and poet Johann Wolfgang von Goethe (1749–1832).
Vivianite (Fe2+
Fe2+
2(PO
4)
2·8H
2O) is a hydrated iron phosphate mineral found in a number of geological environments. Small amounts of manganese Mn2+, magnesium Mg2+, and calcium Ca2+ may substitute for iron Fe2+ in the structure. Pure vivianite is colorless, but the mineral oxidizes very easily, changing the color, and it is usually found as deep blue to deep bluish green prismatic to flattened crystals.
Vivianite crystals are often found inside fossil shells, such as those of bivalves and gastropods, or attached to fossil bone.
Glauconite is an iron potassium phyllosilicate mineral of characteristic green color which is very friable and has very low weathering resistance.
Enstatite is a mineral; the magnesium endmember of the pyroxene silicate mineral series enstatite (MgSiO3) – ferrosilite (FeSiO3). The magnesium rich members of the solid solution series are common rock-forming minerals found in igneous and metamorphic rocks. The intermediate composition, (Mg,Fe)SiO
3, has historically been known as hypersthene, although this name has been formally abandoned and replaced by orthopyroxene. When determined petrographically or chemically the composition is given as relative proportions of enstatite (En) and ferrosilite (Fs) (e.g., En80Fs20).
The chlorites are the group of phyllosilicate minerals common in low-grade metamorphic rocks and in altered igneous rocks. Greenschist, formed by metamorphism of basalt or other low-silica volcanic rock, typically contains significant amounts of chlorite.
Datolite is a calcium boron hydroxide nesosilicate, CaBSiO4(OH). It was first observed by Jens Esmark in 1806, and named by him from δατεῖσθαι, "to divide," and λίθος, "stone," in allusion to the granular structure of the massive mineral.
Allanite (also called orthite) is a sorosilicate group of minerals within the broader epidote group that contain a significant amount of rare-earth elements. The mineral occurs mainly in metamorphosed clay-rich sediments and felsic igneous rocks. It has the general formula A2M3Si3O12[OH], where the A sites can contain large cations such as Ca2+, Sr2+, and rare-earth elements, and the M sites admit Al3+, Fe3+, Mn3+, Fe2+, or Mg2+ among others. However, a large amount of additional elements, including Th, U, Be, Zr, P, Ba, Cr and others may be present in the mineral. The International Mineralogical Association lists four minerals in the allanite group, each recognized as a unique mineral: allanite-(Ce), allanite-(La), allanite-(Nd), and allanite-(Y), depending on the dominant rare earth present: cerium, lanthanum, neodymium or yttrium.
Heulandite is the name of a series of tecto-silicate minerals of the zeolite group. Prior to 1997, heulandite was recognized as a mineral species, but a reclassification in 1997 by the International Mineralogical Association changed it to a series name, with the mineral species being named:
Saponite is a trioctahedral mineral of the smectite group. Its chemical formula is Ca0.25(Mg,Fe)3( 4O10)(OH)2·n(H2O). It is soluble in sulfuric acid. It was first described in 1840 by Svanberg. Varieties of saponite are griffithite, bowlingite and sobotkite.
Illite is a group of closely related non-expanding clay minerals. Illite is a secondary mineral precipitate, and an example of a phyllosilicate, or layered alumino-silicate. Its structure is a 2:1 sandwich of silica tetrahedron (T) – alumina octahedron (O) – silica tetrahedron (T) layers. The space between this T-O-T sequence of layers is occupied by poorly hydrated potassium cations which are responsible for the absence of swelling. Structurally, illite is quite similar to muscovite with slightly more silicon, magnesium, iron, and water and slightly less tetrahedral aluminium and interlayer potassium. The chemical formula is given as (K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2·(H2O)], but there is considerable ion (isomorphic) substitution. It occurs as aggregates of small monoclinic grey to white crystals. Due to the small size, positive identification usually requires x-ray diffraction or SEM-EDS analysis. Illite occurs as an altered product of muscovite and feldspar in weathering and hydrothermal environments; it may be a component of sericite. It is common in sediments, soils, and argillaceous sedimentary rocks as well as in some low grade metamorphic rocks. The iron-rich member of the illite group, glauconite, in sediments can be differentiated by x-ray analysis.
Aerinite is a bluish-purple inosilicate mineral. It crystallizes in the monoclinic system and occurs as fibrous or compact masses and coatings. It has a dark, vitreous luster, a specific gravity of 2.48 and a Mohs hardness of 3.
Babingtonite is a calcium iron manganese inosilicate mineral with the formula Ca2(Fe,Mn)FeSi5O14(OH). 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 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.
Mesolite is a tectosilicate mineral with formula Na2Ca2(Al2Si3O10)3·8H2O. It is a member of the zeolite group and is closely related to natrolite which it also resembles in appearance.
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.
Magadiite is a hydrous sodium silicate mineral (NaSi7O13(OH)3·4(H2O)) which precipitates from alkali brines as an evaporite phase. It forms as soft (Mohs hardness of 2) white powdery monoclinic crystal masses. The mineral is unstable and decomposes during diagenesis leaving a distinctive variety of chert (Magadi-type chert).
Chamosite is the Fe2+end member of the chlorite group. A hydrous aluminium silicate of iron, which is produced in an environment of low to moderate grade of metamorphosed iron deposits, as gray or black crystals in oolitic iron ore. Like other chlorites, it is a product of the hydrothermal alteration of pyroxenes, amphiboles and biotite in igneous rock. The composition of chlorite is often related to that of the original igneous mineral so that more Fe-rich chlorites are commonly found as replacements of the Fe-rich ferromagnesian minerals (Deer et al., 1992).
Green earth, also known as terre verte and Verona green, is an inorganic pigment derived from the minerals celadonite and glauconite. Its chemical formula is K[(Al,Fe3+),(Fe2+,Mg] O102.
Aluminoceladonite is a low-temperature potassium dioctahedral mica mineral which is an end-member in the illite-aluminoceladonite solid solution series. The chemical formula for aluminoceladonite is K(Mg,Fe2+)Al(Si4O10)(OH)2.
Garronite-Ca is a fairly rare silicate mineral, from the zeolite, which has been found in a few dozen locations in the world. It was first found in the Glenariff Valley, Garron Plateau, County Antrim, Northern Ireland, and in some locations in Iceland. The name comes from the town of Garron, in Northern Ireland, which is consequently considered its type locality. The name initially used was that of Garronite, without subfixes, but the discovery in 2015 of a garronite with dominant sodium instead of calcium in the position of interchangeable cations made it necessary to use subfixes, remaining as Garronite-Ca, to distinguish it from the new species, Garronite-Na.
Radioactive 9.11% (K)
