Silicon and oxygen compounds {silicate mineral} are hard and are 1/3 of all minerals. SiO2 [2 is subscript] is triangular. Silicon dioxide is in granite and obsidian. It forms at 600 C to 900 C. It has density 2.7 g/cm^3. SiO4 [4 is subscript] is tetrahedral. Silicon oxides can have another form {tridimyte}. Silicates can be nesosilicate, sorosilicate, cyclosilicate, inosilicate, phyllosilicate, or tektosilicate.
Silicon oxides {silica}| can be grains.
hardness-7 gray silicate {flint}.
Calcium silicate, magnesium silicate, and iron silicate {gabbro} can be together.
Hard glass {rhinestone}| has many colors and is for jewels.
Tetrahedral silicates {sorosilicate} can have two tetrahedra. Zn4Si2O7(OH)2 . H2O [4, 2, and 7 are subscripts] {hemimorphite} {calamine} is sorosilicate, is secondary zinc mineral, and is milk white or blue.
SiO2 . n H2O [2 is subscript] {opal}| is colloidal and can have iridescence {precious opal}, red reflections {fire opal}, or be in trees {wood opal}.
Opal can have glassy appearance {hyalite} in granite.
SiO2 [2 is subscript] {quartz}| has crystals and is glassy or milky {rock crystal}, brown {smoky quartz}, black {morion quartz}, citrine, pink {rose quartz}, amethyst, chalcedony, agate, onyx, or jasper.
Quartz {agate}| can have different color bands.
Quartz {amethyst}| can be violet.
Quartz {chalcedony} can have translucent microcrystals.
Quartz {citrine} can be yellow.
Quartz {jasper} can be many-colored.
Quartz {onyx}| can have straight black-and-white bands.
Tetrahedral silicates {cyclosilicate} can be rings.
CuSiO2(OH)2 [2 is subscript] {dioptase} is copper cyclosilicate and is green.
Be3Al2Si6O18 [3, 2, 6, and 18 are subscripts] {beryl}| is aluminum cyclosilicate and can be hexagonal beryllium ore {pegmatite}, emerald, or aquamarine.
Beryl can be blue minerals {aquamarine, mineral}.
Beryl can be green minerals {emerald}|.
(Na,Ca)(Li,Mg,Fe,Al)3(Al,Fe)6B3Si6O27(O,OH,F)4 [3, 6, and 27 are subscripts] {tourmaline}| is aluminum and iron cyclosilicate and commonly is schorl.
Tourmaline commonly is a black mineral {schorl}.
Triangular silicates {inosilicate} can be long chains.
Inosilicate {pyroxene} can be green or black and granular or fibrous.
CaMgSi2O6 [2 and 6 are subscripts] {diopside} is calcium and magnesium pyroxene.
feldspar and pyroxene mixture {basalt}|.
Inosilicate {amphibole} can be white to black-green.
Hard green amphibole {jade}| is for jewelry.
(Ca,Na,K,Mg,Fe,Al)Si2O6 [2 and 6 are subscripts] {hornblende} is calcium, sodium, potassium, magnesium, iron, and aluminum amphibole and is monoclinic.
Silicates {nesosilicate} can be isolated tetrahedra.
(Mg,Fe)2SiO4 [2 and 4 are subscripts] {olivine}| {chrysolite} {peridotite} is magnesium and iron nesosilicate and is green to yellow-brown. Peridotite igneous rock in mantle can react with seawater to make hydrogen. Hydrogen reacts with carbon-containing molecules to make methane.
CaTiSiO5 [5 is subscript] {titanite} is titanium nesosilicate.
Al2SiO4(OH,F)2 [2 and 4 are subscripts] {topaz, mineral}| is aluminum nesosilicate and can be yellow, amber, or blue. Transparent form {chiastolite} is in Spain.
Fe3Al2(SiO4)3 [3, 2, and 4 are subscripts] {almandine, mineral} is aluminum nesosilicate.
Almandine can be isometric, red, and translucent {garnet}|.
Zr(SiO4) [4 is subscript] {zircon, mineral}| is zirconium nesosilicate and can be orange or red {hyacinth, zircon}.
Zircon can be prismatic {adamantine}.
Triangular silicates {phyllosilicate} can have flat layers.
K2(Mg,Fe,Al)4-6(Si,Al)8O20(OH)4 [2, 4, 6, 8, and 20 are subscripts] {biotite} {black mica} is phyllosilicate and is lustrous and lamellar.
Chlorine-containing phyllosilicates {chlorite} are lamellar and dark green or blue-green.
KAl3Si3O10(OH)2 [3 and 10 are subscripts] {white mica} {mica}| is phyllosilicate and is pearly and lamellar. Aluminum silicates form at 900 C to 1400 C. They have density 2.6 g/cm^3 to 3.5 g/cm^3. Aluminum-silicate compounds include feldspar, hornblende, and biotite. Aluminum silicates with minerals are clays.
Mg3Si2O5(OH)4 [3, 2, 5, and 4 are subscripts] {serpentine, mineral}|, from Alps and Apennines, is phyllosilicate and can be chrysolite, asbestos serpentine, and antigonite.
Mg3Si4O10(OH)2 [3, 4, and 10 are subscripts] {talc}| is phyllosilicate and is white or gray, greasy, and monoclinic.
Talc can form stone {soapstone}|.
Triangular silicates {tektosilicate}, such as feldspar, can be three-dimensional structures. Tektosilicates are the most-common silicates.
feldspar and plagioclase mixture {andesite}.
CaAl2Si2O8 [2 and 8 are subscripts] {anorthite} is tektosilicate.
CaB2Si2O8 [2 and 8 are subscripts] {lazurite} {lapis lazuli}| is tektosilicate, is blue or dark blue, and is granular.
KAlSi3O8 [3 and 8 are subscripts] {orthoclase} is tektosilicate and is monoclinic.
NaAlSi3O8 [3 and 8 are subscripts] {plagioclase} is tektosilicate.
NaCa2Al5Si13O36 . 14 H2O [2, 5, 13, and 36 are subscripts] {stillbite} is tektosilicate and can be zeolite.
Stillbite can be aluminum silicate {zeolite} that swells under heat.
Triangular silicates {feldspathoid} {feldspar}| can be low in silicon. Feldspar is the most-common silicate.
Feldspar {moonstone}| can have pearl luster.
Fine-grained igneous rock has large feldspar crystals {porphyry}.
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Date Modified: 2022.0225