minerals list silicates

sphene

CaTiSiO5 nesosilicate - wedge-shaped crystals, brown, green, yellow color - cross sections are diamond shaped - brown basically, accessory mineral in plutonic felsic ign rocks, mafic met rocks, used for radiometric dating

diopside

CaMgSi2O6 monoclinic clinopyroxene - crystallize firectly from basic magmas - in ultrabasic ign rocks - silicates in dolomitic limestones are metamorphosed and in iron-rich skarns - has right-hand cleavage, lighter green color, crystals rarer

labradorite

(Ca,Na)(Al,Si)4O8 triclinic tectosilicate - schiller or labradorescence from lamellae acting as diffraction gratings - found in more mafic rocks (basalt/gabbro and related) - has striations and cleavage so it's not opal - kinda blue i guess

augite

(Ca,Na)(Mg,Fe,Al)(Si,Al)2O6 clinopyroxene monoclinic - cleavage @right angles like the rest of the pyroxenes - in mafic rocks, metamorphosed mafics, some metacarbonates - phenocrysts in basalt too - recognizable by dark color and blocky, prismatic crystals

olivine

(Mg,Fe)2SiO4 nesosilicate - olive-green color, in ign rocks; peridotite, dunite, basalt, gabbro - orthorhombic, forms short prisms - conchoidal fracture, can look like epidote but epidote has cleavage and different crystal form - equant grains i guess

cummingtonite

(Mg,Fe)7Si8O22(OH)2 iron/magnesium group of amphiboles, columnar, bladed, acicular, elongate parallel to c - good cleavage @56, 124 deg - vitreous, dark brown to green = calcic clinoamphiboles - in metamorphosed mafic, ultramafic rocks

anthophyllite

(Mg,Fe)7Si8O22(OH)2 orthorhombic amphibole/orthoamphibole - brown, off-white grey color - cleavage good in 2D - fibrous masses common, formed by metamorphism - in gneiss, schist (met mafic rocks) - exsolution lamellae apparently - anthophyllite cordierite gneiss a thing

chlorite

(Mg,Fe,Al)3(Si,Al)4O10(OH)2 (Mg,Fe,Al)3(OH)6 TOT + O structure, trioctahedral - fine grained scaly, foliated massive aggregates, can form oolitic/spherulitic balls in sed rocks - flexible but not elastic - in low-med grade pelitic/mafic met rocks; greenschist, alt of biotite, hornblende

garnets - almandine/spessartine/pyrope

(Mg,Fe,Mn)3Al2(SiO4)3 nesosilicate, isometric - red, brown, black orange - in ultramafic igneous rocks, almandine in mica schist/gneiss, spessartine in felsic ign, grossular in metacarbonates - can have zoning

kaolinite

Al2Si2O5(OH)4 TO dioctahedral - formed from weathering of basically every silicate - massive, white, earthy/dull

pyrophyllite

Al2Si4O10(OH)2 phyllosilicate, dioctahedral TOT - monoclinic or triclinic - massive aggregates of mica-like flakes, pearly to dull luster, waxy/greasy feel - uncommon but in low-grade al met rocks or hydrothermal alt of Al minerals (feld, muscovite, Al2O5, corundum, topaz)

topaz

Al2SiO4(F,OH)2 orthorhombic nesosilicate, hydrated - like quartz but different crystal habit, has basal cleavage, high SG, different hardness - in felsic ign rocks, well-formed in vesicles in rhyolitic volcanic, granitic pegmatites - can also be in hydrothermally altered rocks next to granitic intusions - associated w fluorite in pegmatites as well

kyanite

Al2SiO5 stripier and more elongate than sodalite triclinic

andalusite

Al2SiO5 orthorhombic, square cross sections - can get pretty cross on the inside

sillimanite

Al2SiO5, clear needles orthorhombic - like wollastonite and tremolite but only 1 cleavage direction

beryl

Be3Al2Si6O18 hexagonal cyclosilicate - found in granite pegmatites - morganit (maganese) is pink, emerald from chromium, aquamarine is blue - imperfect cleavage, flat pyramid tops - heavier than quartz

anorthite

CaAl2Si2O8 triclinic tectosilicate usually massive, in metamorphozed carbonates - parallel striations on cleavage surfaces distinguish pg from k-feld, also gray color v pink - also in basic rocks (gabbros) that form @high t, lavas, - wacky structure bc Al/Si not in adj tetrahedra - "Al avoidance principle" = Mode IV - heavier than albite - contact twinning

epidote

Ca2(Al,Fe)Al2O(SiO4)(Si2O7)(OH) monoclinic sorosilicate - single cleavage direction, pistachio green, association w garnet and also prehnite apparently - columnar/bladed/elongate, 4-6 sided - perfect basal cleavage, not olivine bc it has cleavage - if massive better "pistachio green" - in metamorphic rocks, pelites, metacarbonates, etc - if Alrich=clinozoisite, Fe=epidote, near hydrothermal/hot solutions

prehnite

Ca2Al(AlSi3O10)(OH)2 phyllosilicate - columnar mases, radiating, globular, vitreous - light green, single good cleavage - form w epidote - in veins/caivites of mafic ign rocks w zeolites - prehnite- pumpellyite facies

zoisite

Ca2Al3Si3O12(OH) sorosilicate - anhedral grains, columnar crystals, acicular, overgrows w epidote possible - one good cleavage, grayish color - in med-grade metaca-rich sed (calcareous shale), amphibolite from maifc, hydrothermal alt of pg - does the watermelon thing w ruby/corundum

tremolite, actinolite

Ca2Mg5Si8O22(OH)2 low-calcium amphibole - nephrite is type of tremolite - dolomites metamorphosed in contact metamorphism - fibrous green crystals are actinolite - i guess lighter than hornblende

wollastonite

Ca2Si2O6 - technically pyroxenoid (3 turns) - bladed, colymnar, elongate - perfect {110} cleavage - looks like tremolite but different cleavage, white-gray/ green, splintery, vitreous - common in metamorphosed carbonates, w carbonates, tremolite, epidotes, diopside, garnet

garnets - andradite/grossular

Ca3(Al,Fe)2(SiO4)3 nesosilicate, isometric - associated w wollastonite, generally metamorphic - generally greenish

lawsonite

CaAl2Si2O7(OH)2H2O hydrous orthorhombic sorosilicate tabular on {010}, prismatic cross section, perfect cleavages @90 deg - colorless, white, blueish green/gray - not zoisite/clinozoisite bc of many cleavages - in glaucophane schist/other low T high P met rocks

spodumene

LiAlSi2O6 monoclinic in Li-rich granite pegmatites, associated w lepidolite mica, tourmaline, beryl, quartx, alite - rough crystals can be huge, violet spodumene kinzite - ID w light color, prismatic, striated crystals, occurence in Li-rich pegmatites w lepidolite mica

leucite

KAlSi2O6 tetragonal tectosilicate - equant crystals or anhedral, vitreous luster, cool crystal habit is ID - in k-rich mafic lava w feldspar, cpx, sodic amphiboles

orthoclase

KAlSi3O8 monoclinic - somewhat ordered, M2/M3 remember - some are microscopically perthic - alt to sericite and clay, ID w right-angle cleavage - yellow, white, in granites and syenites - moonstone is the one w lamellae/intergrowths

sanidine

KAlSi3O8 tectosilicate high P polymorph, most crystallizes in sanidine - symmetry plane {010}, monoclinic - complete disorder - like orthoclase but glassier, can even be transluscent - on volcanic felsic rocks (rhyolite, trachyte)

microcline

KAlSi3O8 triclinic tectosilicate - SALMON PINK - amazonite green-blue var from Pb - granite, syenite, felsic rocks, pelitic rocks, not found in volcanic rocks other than xenoliths - low T, very ordered

phlogopite

KMg3(AlSi3O10)(OH)2 technically Mg endmember of biotite, lighter in color, brown-red hue - common only in ultramafic rocks (peridotites, pyroxenites), and mg rich marbles

lepidolite

K(Li,Al)3(SiAl)4O10(F,OH)2 - pretty pink or lilac color, has darker purple dots, type of mica - forms only in granite pegmatites, may be triboluminescent (flash colors when pressed), also can form w lithium alt muscovite - flakey, pink color, found w other lithium minerals

biotite

K(Mg,Fe)3AlSi3O10(OH)2 trioctahedral TOT + c phlogopite Mg endmember - alt to chlroite, clay, in silic and alkalic ign rocks, metamorphic greenschist, marble/carbonate rocks - darker than muscovite

muscovite

KAl2(AlSi3O10)(OH)2 dioctahedral TOT + c - lighter than biotite, talc/pyrophyllite are greasy, layers elastic - in plutonic felsic ign rocks, metamorphic rocks, common in arkose

cordierite

Mg2Al3[AlSi5]O18 orthorhombic - looks like quartz but more blue - in med-high grade pelitic met rocks, porphyroblasts in hornfels, w chlorite, Al2SO5, staurolite, micas - has different cleavage than glaucophane

serpentine

Mg3Si2O5(OH)4 TO trioctahedral - chrysolite, antigorite, lizardite var. (differnet in structure) - in hydrothermal alt of mafic/ultramafic, w talc, calcite, chlorite, brucite, magnetite, metamorphosed carbonate rocks - lizardite platy, chrysolite asbestiform, antigorite corrugated ID w softness, platy texture, association w talc

talc

Mg3Si4O10(OH)2 phyllosilicate, trioctahedral TOT foliated, radiating aggregates, sectile/waxy feel - monoclinic, soapy feel, white or light grey, mixed w green chlorite - hydrothermal alt mafic rocks, from dolomite metamorphism (w calc-silicate minerals), talc schist - associated w serpentine, chlorite

rhodonite

MnSiO3 pyroxenoid; distorted chains w 5-turn massive ganular aggregates, triclinic - can alt to rhodochrosite/Mn oxides/hydroxides - ID w pink color, rose red - not rhodochrosite bc of different crystal system, generally granular unlike rhodochrosite - in Mn hydrotheraml systems, skarns

glaucophane

Na2Mg3Al2Si8O22(OH)2 monoclinic sodic amphibole can be tiger's eye wth fibrous var reibeckite - distinctive blue - not sodalite bc sodalite is granular, also darker than sodalite? - in high-p low T met rocks w lawsonite, chlorite, albite, quartz, jadeite, also alkali ign rocks - bladed to slender prismatic crystals, also fibrous/granular - gets darker w the more Fe (reibeckite)

nepheline

Na3K(Al4Si4O16) hexagonal tectosilicate generally anhedral, but crystals are 6-sided, mostly white intergrowths, greasy luster, poor cleavage - can alt to clay minerals, sodalite, calcite - common in calc-silicate ign rocks (syenite) w feldspare, biotite, amphibole

sodalite

Na8Al6Si6O24Cl2 isometric tectosilicate - generally massive, fluouresces - lapis lazuli (contact met of limestone), alkali rich plutonic ign si deficient rocks - blue color, poor cleavage, conchoidal, has cross cutting intrusions a lot lazurite is SO4 instead of Cl2, so it's found w pyrite

jadeite

NaAlSi2O6 monoclinic - omphacite between augite and jadeite, but not solid solution - stubby to elongate w 4/8 sided cross section, but mostly anhedral - if polished can look oily, heavier than nephrite - very nice green color

albite

NaAlSi3O8 triclinic tectosilicate - @high T, solid solution w K feld; low T get exsolution lamellae = perthite (albite lamellae in K-feld) - antiperthite (K-feld lamellae in albite) - high albite: med Al/Si ordering (M2/M3) in volcanic rocks, low labite w high Al/Si ordering --> triclinic (M3) - found in ign, metamorphic rocks, in pegmatites can be bladelike = clevelandite, generally in more felsic rocks - can form crysals but rare - striations and cleavage disinguishing from k-feld, quartz - contact twinning

agate/onyx

SiO2 - in volcanic and metamorphic rocks - traces of Fe, Mn create bands - in cavities in basalt - silica/impurities diffuse in, create bands - onyx technically alternating white and black bands but it's also an agate

jasper

SiO2 aggregate of chalcedony, opaque, impure silica due to clay, iron impurities - also bloodstone - main component in silica-rich parts of BIFs - streak always white

citrine

SiO2 lemon-like pale yellow, color from iron hydroxides, pseudohexagonal

rose quartz

SiO2 massive, crystals rare, color from minute rutile needles - in pegmatites generally

amethyst

SiO2 purple - violet color from irradiation, impurities, other trace elements - crytalline

opal

SiO2·nH2O technically a mineraloid bc amorphous - in limestone, sandstone, rhyolite, basalt - iridescent opal = play of color from hcp/ccp causing intereferene and diffraction - if not iridescent can be white, blue-green, everything else

zircon

ZrSiO4 nesosilicate - good for radiometric dating - basically in all the hecking rocks - no cleavage - tetragonal prismatic crystals; gray, yellow, bwon, no cleavage - METAMICT

staurolite

almost always forms short, prismatic crystals. It's usually brown, and sometimes forms cruciform twins. - in med-grade pelitic met rocks w garnet, cordierite, al silicates, micas

tourmaline

extremely variable when it comes to color, long prismatic crystals with vertical striations on surface - chemical zoning indicated by color variation - black color = schorl - rounded triangle cross sections - schorl like hornblende but doesn't have good cleavage - in granite megmatites, rock hydrothermally altered next to pegmatite, accessory in met rocks

hornblende

green brown to black, white-gray streak, vitreous luster, 5-6 hardness, cleavage at an angle, bladed crystals - cleavage like >90 i think, calcium-rich amphibole - in intermediate ign rocks, med-high grade met terranes - crystals rare but breaks into wedge shapes stubby, prism shaped, monoclinic

milky quartz

hard white or colorless mineral consisting of SiO2, found widely in igneous, metamorphic, and sedimentary rocks - white color from inclusions of gas, liquid, both - crystalline

zeolites - heulandite

hydrated calcium sodium aluminum tectosilicate - creamy colored crystals, pearly sheen, coffin-shaped crystals - from hydrothermal solution perlocating through volcanic rocks (esp basalts), form in caivities left there - also mild metamorphism, deccan traps

zeolites - stilbite

hydrated sodium calcium aluminum tectosilicate - crystals grow in shapes resembling wheat sheave or a stack of bow ties - generally whiteish, oragnish - cavities in basaltic lava, hydrothermal alt, metamorphism

tiger's eye

quartz replacement of fibrous crocidolite asbestos, streak=yellow brown, chatoyant with asbestos needles, gold yellow, gold brown - cat's eye is w like chrysoberyl!

scapolite

tetragonal, unsaturated (Ca,Na)Al12-xSixO24Cl tetragonal crystals, fluoresces orange to yellow in bright UV light - generally in contact/ragional met rocks from calcareous sediments - skarn, metagabbros

sericite

white fine-grained mica, common alt mineral-ish