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Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al 2 Si 2 O 5 ( OH) 4 ), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces . Clay minerals form in the presence of water [ 1] and have been important to life, and many theories of ...
A Quaternary clay deposit in Estonia, laid down about 400,000 years ago. Clay is a type of fine-grained natural soil material containing clay minerals [ 1] (hydrous aluminium phyllosilicates, e.g. kaolinite, Al 2 Si 2 O 5 ( OH) 4 ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities ...
Kaolinite ( / ˈkeɪ.ələˌnaɪt, - lɪ -/ KAY-ə-lə-nyte, -lih-; also called kaolin) [ 5][ 6][ 7] is a clay mineral, with the chemical composition: Al 2 Si 2 O 5 ( OH) 4. It is a layered silicate mineral, with one tetrahedral sheet of silica ( SiO4) linked through oxygen atoms to one octahedral sheet of alumina ( AlO6 ).
Aquamarine variety of beryl with tourmaline on orthoclase. Arsenopyrite from Hidalgo del Parral, Chihuahua, Mexico. Aurichalcite needles spraying out within a protected pocket lined by bladed calcite crystals. Austinite from the Ojuela Mine, Mapimí, Durango, Mexico. Ametrine containing amethyst and citrine, from Bolivia.
Smectite. A smectite (from Ancient Greek σμηκτός (smēktós) 'lubricated'; from σμηκτρίς (smēktrís) 'walker's earth, fuller's earth '; lit. 'rubbing earth; earth that has the property of cleaning') [ 1] is a mineral mixture of various swelling sheet silicates ( phyllosilicates ), which have a three-layer 2:1 (TOT) structure and ...
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.
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. Chlorite minerals show a wide variety of compositions, in which magnesium, iron, aluminium ...
Clastic rock. A thin section of a clast (sand grain), derived from a basalt scoria. Vesicles (air bubbles) can be seen throughout the clast. Plane light above, cross- polarized light below. Scale box is 0.25 mm. Clastic rocks are composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus ...