Rocks {mineral} have definite chemical composition. People know properties of 2000 minerals. Main elements in rocks are oxygen 48%, silicon 28%, aluminum 8%, iron 5%, sodium, magnesium, sulfur, and calcium. Together, they are 98% of crust.
types
Elements make pure minerals, like gold and copper. Sulfides, selenides, tellurides, arsenides, antimonides, and bismuthides are similar. Halides are similar. Oxides and hydroxides are similar. Carbonates, borates, and nitrates are similar, but borates and nitrates are rare. Sulfates, tellurates, chromates, molybdates, and tungstates are similar. Phosphates, arsenates, and vanadates are similar. Silicates are similar and include nesosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, and tektosilicates.
color
Rocks have color and color under fluorescence.
crystal form
Most rocks are crystals {crystal form}, such as cubic crystal, with definite geometry.
density
Rocks have definite specific gravity, depending on composition and crystal structure.
homogeneous mineral
Most minerals {homogeneous mineral} are the same throughout, but bauxite, sand, granite, and porphyry are not homogeneous.
melting
Most rocks have exact melting points, but glasses, resins, and colloids have melting-point ranges.
particle size
Minerals have particle sizes. Clay has fine, cohesive particles. Silt has cohesive particles. Sand has grains. Gravel has small rocks.
refraction
Rocks have definite refractive index.
Materials can emit trapped gases over time {outgas}|.
Crystal form determines flat-surface shape {fracture plane} that appears after breaking rock.
Rocks, such as diamond, can be shiny and lustrous {luster}|. Metals, such as silver, can be lustrous, because dielectric constant is negative.
Some rocks split light into two colors {pleochroism}.
Rocks have relative strength {hardness}|, depending on chemical-bonding patterns.
Hardness scale {Moh's scale} {Moh scale} goes from 1 to 10. Diamond is 10. Cubic boron nitride is 9.5. Corundum is 9. Quartz is 7. Glass is 6. Steel is 5. Fluorite is 4. Calcite is 3. Salt is 2. Talc is 1.
Rocks can have biconvex-lens shapes {lenticular}.
Rocks can be concentric with radial arms {rosette}.
Rocks {sphenoid rock} can have wedge shapes.
Rocks can be needle-like {acicular}.
Rocks can be chalky {calcareous}.
Rocks can have powdery surface crust {efflorescence, rock}.
Rocks can have surface film {patina}|.
Rocks, such as obsidian, can be glass-like {vitreous, rock}|.
Rocks can have built-up masses {concretion}| around them.
Rocks {druse}| can have crystal linings.
Rocks {lacustrine mineral} can form in lakes.
Pure silicon can form very low-density gel {aerogel}.
Minerals {basic mineral} can have low silica content.
Compounds with group VII elements {halide mineral} have low hardness, low density, and vitreous luster. NaCl {halite} has sodium and chloride. KCl {sylvite} has potassium and chloride. CaF2 [2 is subscript] {fluorite} has calcium and fluoride.
Most elements {metal, mineral} are shiny, hard, electric-charge conducting, and heat conducting.
Aluminum comes from aluminum oxide in bauxite.
Calcium is from limestone.
Gold is pure in Latin America, California, Australia, Alaska, and South Africa.
Iron is from iron oxides.
Manganese comes from ocean-floor nodules.
Mercury comes from cinnabar.
Coking coal or freezing air frees nitrogen.
Phosphorus comes from calcium phosphates in limestone deposits.
Potassium comes from many rock types. Potassium-40 is radioactive.
Sulfur is half as free sulfur and half as metal sulfides, in Gulf of Mexico, Italy, Japan, and Russia.
Tin comes from cassiterite.
Scheelite is tungsten ore.
Uranium is in Congo, Romania, Canada, and Colorado.
Zinc comes from zinc oxides.
Compounds {phosphate mineral} with phosphorus and oxygen are secondary minerals and have color. Phosphates include apatite, turquoise, and autunite.
Unlike most substances, some crystals {Rochelle salt} become less symmetrical and more ordered at high temperature.
Carbon-oxygen compounds {carbonate mineral} can have medium or low hardness, be white or highly colored, and effervesce if dissolved in hydrochloric acid. Calcite has calcium and is the most-common mineral, as chalk and limestone. Dolomite has calcium and magnesium and is second most-common mineral. Carbonates include siderite, magnesite, cerussite, azurite, malachite, soda, and borax.
Na2CO3 [2 and 3 are subscripts] {soda}| has sodium and is hydrous.
Compounds {oxide mineral} with oxygen vary. Oxides include bauxite, spinel, magnetite, chromite, corundum, cuprite, zincite, hematite, rutile, cassiterite, and uraninite.
BaSO4 [4 is subscript] {barite} is main barium ore.
SnO2 [2 is subscript] {cassiterite} is main tin ore.
TiO2 [2 is subscript] {rutile} has titanium and is semiconductor. It can catalyze water to oxygen and hydrogen under ultraviolet light {photolysis}, and organic molecules to carbon dioxide and water under ultraviolet light, by making superoxide and hydroxyl radicals. Titania thin films make things wettable {wettability} and so self-cleaning.
Aluminum or iron oxides can form rocks {spinel} that have no cleavage.
UO2 [2 is subscript] {uraninite} has uranium.
Manganese oxide can be in hydrous ore {wad}.
Compounds {sulfate mineral} with sulfur and oxygen have low hardness, have vitreous luster, and are not opaque. Sulfates include anhydrite, gypsum, selenite, alabaster, barite, and jarosite.
Hydrous NaAlSO4, KAlSO4, and NH4AlSO4 [4 is subscript] {alum} are aluminum sulfates with sodium, potassium, and ammonia. Alum treats canker sores and is for water purification. Aluminum potassium sulfate is AlK(SO4)2 [4 and 2 are subscripts].
Hydrous sulfates {vitriol} are secondary minerals formed in ore and can be green or blue-green {iron vitriol}, white {zinc vitriol}, pale green {nickel vitriol}, or blue {copper vitriol}.
Compounds {sulfide mineral} with sulfur have metallic luster. Sulfides include pyrite, chalcopyrite, galena, cinnabar, molybdenite, argentite, and marmatite.
Ag2S [2 is subscript] {argentite} has silver.
HgS {cinnabar}| is the most-important mercury ore.
MoS2 [2 is subscript] {molybdenite} is the most-common molybdenum mineral.
Sb2S [2 is subscript] {stibnite} has antimony.
Aluminum-oxide, iron-hydroxide, and silicate mixture {bauxite}| is main aluminum ore and is mainly in Yugoslavia, France, Italy, and Guyana.
BeAl2O4 [2 and 4 are subscripts] {chrysoberyl} {alexandrite} has beryllium and aluminum and makes violet gems and cat's eyes.
Al2O3 [2 and 3 are subscripts] {corundum} {emery} has aluminum.
Corundum can be red transparent jewels {ruby, mineral}|.
Corundum can be blue jewels {sapphire}|.
Na2BO3 hydrous [2 and 3 are subscripts] {borax}| is colorless, translucent, and hydrous.
Calcium and boron carbonate fibers {ulexite} {television stone} let light travel through their fibers.
CaSO4 [4 is subscript] {anhydrite} has calcium.
Ca3F(PO4)3 [3 and 4 are subscripts] {apatite} has calcium and iron and is yellow-green.
Ca(UO2)2(PO4)2 . 12 H2O [2 and 4 are subscripts] {autunite} has calcium and uranium oxide and is hydrous.
CaMg(CO3)2 [3 and 2 are subscripts] {dolomite}| has calcium and magnesium and is second most-common mineral.
CaWO4 [4 is subscript] {scheelite} is tungsten ore.
CaCO3 [3 is subscript] {calcite} has calcium and is the most-common mineral, as chalk and limestone.
Calcite {limestone}| is the most-common mineral.
CaSO4 . 2 H2O [4 and 2 are subscripts] {gypsum}| has calcium and is hydrous, colorless, laminar, and light. It can be selenite and alabaster.
Gypsum can be layered, compacted, and colored {alabaster, mineral}.
Gypsum can be individual crystals {selenite}.
Starting 345,000,000 years ago, swamps formed and sea sediments covered them hundreds of times, making many rock and dead-plant layers. Layer weight created high pressure that changed organic matter into carbon forms {carbon mineral}.
types
Under pressure, organic matter turns slowly into first peat, then lignite, then bituminous coal, and then anthracite coal, as it becomes more crystalline.
coal
Many places that used to be under sea have coal, such as USA, Canada, England, and Russia.
petroleum
Decaying organic matter trapped in anti-clinal deposits became petroleum, with natural gas above it, as in Saudi Arabia, Middle East, and Russia.
diamond
Diamonds are covalently bound pure carbon and form at 5000 F and 1,000,000 lb/in^2 pressure, 240 miles below surface. Almost all diamonds are in South Africa. Diamond size is by weight {carat}.
graphite
Graphite is soft carbon. Hexagon graphite layers include heptagons, resulting in negative curvature. Hexagon graphite layers include pentagons, resulting in positive curvature.
Pure carbon can be amorphous {amorphous carbon}, with diamond bonds and graphite bonds.
Pure carbon can form into balls {buckyball} {buckminsterfullerene} with five-carbon and six-carbon rings, like soccer ball hexagons and pentagons.
Pure carbon can form low-density gel {carbon aerogel}.
Yams, soybeans, and tropical plants have lower carbon-13 to carbon-12 ratio than temperate-zone plants {carbon isotope ratio test} (CIR).
Pure graphite hit by meteorites forms hexagonal structure {chaoite}.
Pure carbon fibers can have small plates in chains {filamentous carbon}.
Pure carbon {graphene} can form plane hexagonal arrays. Array is flexible but stronger than diamond. Graphene has strong bonds and flexibility and so rarely has missing atoms or impurities. Graphene conducts electricity fastest, because bonds are strong and crystal defects are few. Charge carriers move at 1/300 light speed and have relativistic effects.
Pure carbon can form hexagonal-pattern diamonds {lonsdaleite} {hexagonal diamond}.
Pure carbon can form aerogel-like structure {nanofoam} that is ferromagnetic.
Pure carbon can make material {nanorod} harder than diamond.
Pure carbon can form into six-carbon-ring tubes {buckytube} {nanotube, carbon}, 10 or more carbons diameter, 10000 carbons long, strong, heat-resistant, radiation-resistant, resilient, flexible, conducting or semiconducting, and nested or single (Sumio Iijima) [1991]. Random nanotubes arrangements {nanonet} conduct electricity.
Pure carbon can form hexagonal structure {schwartzite} with included heptagons.
Cu3(CO3)2(OH)2 [3 and 2 are subscripts] {azurite} is blue copper ore and is hydrous.
Cu2S [2 is subscript] {calcocite} has copper.
CuFeS2 [2 is subscript] {chalcopyrite} is the most-common copper ore.
Cu2O [2 is subscript] {cuprite} has copper.
Cu2CO3(OH)2 [2 and 3 are subscripts] {malachite} has copper, is green, and is hydrous.
CuAl6(PO4)4(OH)8 . 5 H2O [6, 4, 8, and 2 are subscripts] {turquoise, mineral}| has copper, is hydrous, and is sky blue. It is in Iran, Siberia, Turkestan, New Mexico, and Arizona.
FeCr2O4 [2 and 4 are subscripts] {chromite} has iron and chromium and can be spinel {ruby spinel} {balas ruby}.
Fe2O3 [2 and 3 are subscripts] {hematite} {oligist} is iron ore.
KFe3(SO4)2(OH)6 or NaFe3(SO4)2(OH)6 or AgFe3(SO4)2(OH)6 or PbFe3(SO4)2(OH)6 [3, 4, 2, 6, and 3 are subscripts] {jarosite} are iron sulfates with potassium, sodium, silver, or lead.
Iron oxides can be hydrous ores {limonite}.
Fe3O4 [3 and 4 are subscripts] {magnetite} has iron and is spinel.
ZnFeS2 [2 is subscript] {marmatite} has zinc and iron.
FeS2 [2 is subscript] {pyrite}| {fool's gold} has iron and is the most-common sulfide.
FeCO3 [3 is subscript] {siderite} is minor iron ore.
PbCO3 [3 is subscript] {cerussite} is lead ore.
PbS {galena} has lead and often associates with silver.
MgSO4 . 7 H2O [4, 7, and 2 are subscripts] {epsonite} {Epsom salt}| has magnesium, is hydrous, forms by evaporation, and is white.
MgCO3 [3 is subscript] {magnesite} has magnesium.
ZnS {sphalerite} {zincblende} {schalenblende} has zinc.
ZnO {zincite} has zinc.
Rocks are inorganic, but living things make resin, bitumen, and amber {organic mineral}.
Living things make minerals {amber, mineral}.
Dead living things can form minerals {bitumen}|.
Rocks {lagerstätten} can retain traces of soft-bodied animals and animal burrows. Solnhofen Limestone in Germany has fossil Archaeopteryx. Burgess Shale in British Columbia, Canada, has Cambrian fossils. Chienjiang in Yunnan Province, China, has early Cambrian fossils. Doushantuo Formation in Guizhou Province, China, has early Precambrian fossils in calcium phosphate. Ediacara Hills in Australia have Precambrian fossils.
pearl-oyster inside shell {nacre} {mother-of-pearl}|.
pearl-oyster round excretion {pearl, gem}|.
Plants make minerals {resin, mineral}|.
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}.
Rocks {rock, types} can be igneous, metamorphic, or sedimentary.
Molten minerals from mantle cool and harden at different rates to make rock {igneous rock}|.
Igneous-rock slow cooling makes coarse grain crystals {granite}|.
dark, hard, smooth {diorite}.
Igneous-rock rapid cooling makes fine grain crystals {obsidian}.
Rhyolite {pumice} can form with gas bubbles.
Fine-grained glassy granite {rhyolite} has color bands.
Basalt lava flows have red-brown, porous rocks {scoria} that contain gas bubbles.
Igneous rocks {sialic rock} can be mostly silicon and aluminum. Granite, continental rock, and sediments are sialic.
soft volcanic rock {tufa}.
aerated light volcanic rock {tuff}.
Sand or clay layers can make rock {sedimentary rock}|. Water, wind, or ice makes sand or clay layers. Layers can be clastic rock, crystallize from shallow lakes or seas by evaporation to make sediment, or precipitate to make sediment. Sedimentary rocks can be calcite limestone and calcium-and-magnesium carbonate dolomite. Sedimentary rocks are the only rocks that have no reheating, so they can retain fossil imprints.
Layers can cement together by pressure {clastic rock}.
Sedimentary rocks {conglomerate rock} can come from stones and gravel in hardened clay.
Sedimentary rocks {sandstone}| can come from sand.
Sedimentary rocks {shale}| can come from clay and wood.
Igneous or sedimentary rocks can change to new forms {metamorphic rock}| by heat and pressure deep in Earth.
Metamorphic rocks {breccia} can come from conglomerate.
Metamorphic rocks {diabase} can come from basalt.
Metamorphic rocks {gneiss} can come from granite.
Metamorphic rocks {marble}| can come from limestone or dolomite.
Metamorphic rocks {quartzite} can come from sandstone.
Metamorphic rocks {schist}| can come from shale and basalt.
Metamorphic rocks {slate, rock}| can come from clay or shale.
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Date Modified: 2022.0225