Talc, or talcum, is a clay mineral composed of hydrated magnesium silicate, with the chemical formula Mg3Si4O10(OH)2. 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.
Chrysotile or white asbestos is the most commonly encountered form of asbestos, accounting for approximately 95% of the asbestos in the United States and a similar proportion in other countries. It is a soft, fibrous silicate mineral in the serpentine subgroup of phyllosilicates; as such, it is distinct from other asbestiform minerals in the amphibole group. Its idealized chemical formula is Mg3(Si2O5)(OH)4. The material has physical properties which make it desirable for inclusion in building materials, but poses serious health risks when dispersed into air and inhaled.
Peridotite ( PERR-ih-doh-tyte, pə-RID-ə-) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high proportions of magnesium-rich olivine, with appreciable iron. Peridotite is derived from Earth's mantle, either as solid blocks and fragments, or as crystals accumulated from magmas that formed in the mantle. The compositions of peridotites from these layered igneous complexes vary widely, reflecting the relative proportions of pyroxenes, chromite, plagioclase, and amphibole.
Garnierite is a general name for a green nickel ore which is found in pockets and veins within weathered and serpentinized ultramafic rocks. It forms by lateritic weathering of ultramafic rocks and occurs in many nickel laterite deposits in the world. It is an important nickel ore, having a large weight percent NiO. As garnierite is not a valid mineral name according to the Commission on New Minerals, Nomenclature and Classification (CNMNC), no definite composition or formula has been universally adopted. Some of the proposed compositions are all hydrous Ni-Mg silicates, a general name for the Ni-Mg hydrosilicates which usually occur as an intimate mixture and commonly includes two or more of the following minerals: serpentine, talc, sepiolite, smectite, or chlorite, and Ni-Mg silicates, with or without alumina, that have x-ray diffraction patterns typical of serpentine, talc, sepiolite, chlorite, vermiculite or some mixture of them all.
Tremolite is a member of the amphibole group of silicate minerals with composition: Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2. Tremolite forms by metamorphism of sediments rich in dolomite and quartz. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy white, but the color grades to dark green with increasing iron content. It has a hardness on Mohs scale of 5 to 6. Nephrite, one of the two minerals known as the gemstone jade, is a green variety of tremolite.
Diopside is a monoclinic pyroxene mineral with composition MgCaSi
2O
6. It forms complete solid solution series with hedenbergite and augite, and partial solid solutions with orthopyroxene and pigeonite. It forms variably colored, but typically dull green crystals in the monoclinic prismatic class. It has two distinct prismatic cleavages at 87 and 93° typical of the pyroxene series. It has a Mohs hardness of six, a Vickers hardness of 7.7 GPa at a load of 0.98 N, and a specific gravity of 3.25 to 3.55. It is transparent to translucent with indices of refraction of nα=1.663–1.699, nβ=1.671–1.705, and nγ=1.693–1.728. The optic angle is 58° to 63°.
Serpentinite is a metamorphic rock composed predominantly of one or more serpentine group minerals formed by near to complete serpentinization of mafic to ultramafic rocks. Its name originated from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called serpentine or serpentine rock, particularly in older geological texts and in wider cultural settings.
Serpentinization is a hydration and metamorphic transformation of ferromagnesian minerals, such as olivine and pyroxene, in mafic and ultramafic rock to produce serpentinite. Minerals formed by serpentinization include the serpentine group minerals, brucite, talc, Ni-Fe alloys, and magnetite. The mineral alteration is particularly important at the sea floor at tectonic plate boundaries.
Anthophyllite is an orthorhombic amphibole mineral: ☐Mg2Mg5Si8O22(OH)2 (☐ is for a vacancy, a point defect in the crystal structure), magnesium iron inosilicate hydroxide. Anthophyllite is polymorphic with cummingtonite. Some forms of anthophyllite are lamellar or fibrous and are classed as asbestos. The name is derived from the Latin word anthophyllum, meaning clove, an allusion to the most common color of the mineral. The Anthophyllite crystal is characterized by its perfect cleavage along directions 126 degrees and 54 degrees.
Serpentine soil is an uncommon soil type produced by weathered ultramafic rock such as peridotite and its metamorphic derivatives such as serpentinite. More precisely, serpentine soil contains minerals of the serpentine subgroup, especially antigorite, lizardite, and chrysotile or white asbestos, all of which are commonly found in ultramafic rocks. The term "serpentine" is commonly used to refer to both the soil type and the mineral group which forms its parent materials.
Talc carbonates are a suite of rock and mineral compositions found in metamorphosed ultramafic rocks.
Heazlewoodite, Ni3S2, is a rare sulfur-poor nickel sulfide mineral found in serpentinitized dunite. It occurs as disseminations and masses of opaque, metallic light bronze to brassy yellow grains which crystallize in the trigonal crystal system. It has a hardness of 4, a specific gravity of 5.82. Heazlewoodite was first described in 1896 from Heazlewood, Tasmania, Australia.
Balangeroite is found in one of the most important chrysotile mines in Europe, the Balangero Serpentinite. Hence, it is usually mistaken as an asbestiform in an assemblage of other mineral phases like chrysotile, magnetite and Fe-Ni alloys. However, Balangeroite does not lead to serious health problems caused by asbestos fibers.
The Merlis Serpentinites are an aligned group of small serpentinite outcrops in the northwestern French Massif Central. Their parent rocks were peridotites from the upper mantle.
The Coal Creek Serpentinite(Coal Creek Serpentine) is a name for a Precambrian rock formation that outcrops on the southeastern side of the Llano Uplift in Gillespie and Blanco counties, Texas. The Coal Creek Serpentinite is tabular south-dipping body of serpentinite. Its outcrop is about 3.7 mi (6.0 km) long along an east–west axis and varies in width from 0.3 to 1.4 mi (0.48 to 2.25 km). Along the central part of the body, the southern contact of the serpentinite slopes about 60° to the south and gradually decreases in dip to about 40° further west. The southern and northern contacts are shear zones. The serpentinite underlies a very sparsely vegetated east–west trending ridge.
The Staten Island Serpentinite locality is a southward extension of the New England Uplands, adjacent to the Manhattan Prong. It includes Todt Hill on Staten Island, which is the highest point along the Atlantic Seaboard south of Maine, at 410 feet (120 m) above sea level. "Todt" is a Dutch word meaning "dead." This hill perhaps received its name from the Dutch settlers because the hilltops overlooking The Narrows consisted of scattered treeless rocky exposures. The chemical character of the bedrock was, in part, the reason for this. Much of Staten Island is covered by the Harbor Hill moraine, the terminal moraine of the last Wisconsin Stage glacier. However, ledges of bedrock consisting of serpentinite are exposed throughout the upland areas on Staten Island. Grymes Hill, the second highest point on Staten Island and just a few miles from Todt Hill has similar bedrock characteristics. Serpentine, the dominant mineral in serpentinite, is rich in magnesium, an element that most plants cannot tolerate in high concentrations. The enrichment of magnesium in the thin serpentine soil covering the glacier-scoured hilltops is probably responsible for the original barren exposures on Todt Hill.
Antigorite is a lamellated, monoclinic mineral in the phyllosilicate serpentine subgroup with the ideal chemical formula of (Mg,Fe2+)3Si2O5(OH)4. It is the high-pressure polymorph of serpentine and is commonly found in metamorphosed serpentinites. Antigorite, and its serpentine polymorphs, play an important role in subduction zone dynamics due to their relative weakness and high weight percent of water (up to 13 weight % H2O). It is named after its type locality, the Geisspfad serpentinite, Valle Antigorio in the border region of Italy/Switzerland and is commonly used as a gemstone in jewelry and carvings.
Lizardite is a mineral from the serpentine subgroup with formula Mg3(Si2O5)(OH)4, and the most common type of mineral in the subgroup. It is also a member of the kaolinite-serpentine group.
Taiwan Black Jade is a type of serpentine jade, primarily composed of minerals such as antigorite and magnetite. It exhibits colors ranging from dark green to black. It is found in the Fengtian area of Hualien County, Taiwan. It was discovered during the mining of Taiwan Jade in the 1960s and 1970s but was not at that time recognized as a new variety of mineral. In the 2010s researchers conducted studies and analysis that identified it as a new type of serpentine jade.
