important minerals + crystal systems

wollastonite

CaSiO3 inosilicate, TRICLINIC the tip of the pyroxene triangle except it's not considered pyroxene bc of the turn thing from thermally metamorphosed impure limestone/dolomite it's very white, three tetrahedra in a turn instead of two like other pyroxenes

sphene (titanite)

CaTiSiO4 monoclinic thorium can sub in calcium so it can be radioactive mostly used for titanium dioxide

cordierite

(Mg,Fe)2Al4Si5O18 cyclosilicate, orthorhombic from contact/regional metamorphism of fine-grained sed rock, like hornfels associated w garnet

hypersthene (orthopyroxene)

(Mg,Fe)SiO3 single chain inosilicate, orthorhombic orthopyroxene is inbetween enstanite (MgSiO3) and ferrosilite (FeSiO3) important in granulite, gabbro, diorite mostly just catagorized by %enstantite%ferrosilite, the bottom "side" of the pyroxene quad/triangle

chlorite

(Mg,Fe,Al)6(Si,Al)4O10(OH)8 or this ig (Mg,Fe)3(Si,Al)4O10(OH)2·(Mg,Fe)3(OH)6 monoclinic phyllosilicate have 2:1 sandwich structure (tetrahedral:octohedral:tetrahedral) - chlorite's interlayer space is filled by the (Mg,Fe)3(OH)6 (the octohedral part) hardness of 2-2.5

hornblende

(Na,K)0-1 Ca2 (Mg,Fe,Al)5 Si6-7 Al2-1 O22 (OH,F)2 not rly a mineral but it's basically a dark amphibole monoclinic inocsilicate many minerals in the series that aren't worth memorizing

orthorhombic crystal system

- 3 axes (mutually perpendicular) that are all not the same length - all axis are perp to each other - has body-centered crystal system

cubic crystal system

- a.k.a. the isometric system - complete symmetry - three crystallographic axes, perpendicular to each other, as well as all equal in length - has body-centered crystal system

trigonal/rhombohedral crystal system

- all three axes are equal in length - none of the axes are perpendicular to each other

triclinic crystal system

- all three axes are not the same length - none of the axes are perpendicular to each other - most "disordered"

monoclinic crystal system

- all three axes are not the same length - two of three axes are perpendicular to each other (the other is not)

tetragonal crystal system

- simple cubic shape extended along its vertical axis to create a rectangular prism - two axis are the same length one isn't - square base and top, 3 axes (one perpendicular, 2 horizontal) - all axis are perpendicular to one another - has body-centered crystal system

kaolinite

Al2Si2O5(OH)4 triclinic phyllosilicate SiO4 linked through oxygen atoms to one octohedral sheet of alumina (AlO6) low cation exchange capacity

topaz

Al2SiO4(F,OH)2 hardest silicate mineral nesosilicate; orthorhombic found in pegmatites a lot

sillimanite

Al2SiO5 nesosilicate, orthorhombic found in gneiss and granulite high temp

kyanite

Al2SiO5 nesosilicate, triclinic very high pressure occurs frequently w staurolite HARNESS OF 5 on one side and 7 on another occurs in gneiss, schist, pegmatites

andalusite

Al2SiO5 orthorhombic, nesosilicate low pressure and technically lower temp very associated w mica schist

diopside

CaMgSi2O6 monoclinic single chain inosilicate forms solid solution series w hedenbergite FeCaSi2O6 and augite found in ultramafic rocks, precursor of chrysolite (Mg endmember of monoclinic pyroxene group) LEFT UP corner of pyroxene quad

beryl

Be3Al2Si6O18 cyclosilicate, hexagonal also can be an ore source of beryllium granite pegmatites, mica schists aquamarine is the blue variety emerald is green beryl w CHROMIUM morganite is pink beryl from MAGANESE 2+ red beryl is red from MAGANESE 3+

hedenbergite

CaFeSi2O6 monoclinic single chain inoslicate, (Ca endmember of monoclinic pyroxene group) contact metamorphism rocks high in iron RIGHT UP corner of pyroxene quad stability more dependent on temp vs pressure, also rarely occurs alone

epidote

Ca2(Al,Fe)Al2O(SiO4)(Si2O7)(OH) it is virteous sorosilicate, monoclinic metamorphosed mineral, also hydrothermal alteration, marble

actinolite

Ca2(Mg,Fe)5Si8O22(OH)2 monoclinic inosilicate found in metamorphic rocks, contact aureoles, also metamorphism of dolostone

clinozoisite

Ca2Al3(SiO4)(Si2O7)O(OH) part of the epidote group - forms solid solution series w epidote by substitution of iron w alluminum sorosilicate, monoclinic occurs in rocks w low/medium grade regional metamorphism/contact metamorphism of high calcium sed rocks

tremolite

Ca2Mg5Si8O22(OH)2 monoclinic, inosilicate found in contact metamorphic rocks in hornfels, skarns, serpentine deposits. also in marble, and a secondary mineral in igneous basalt/diabase vitreous, silky forms in series w actinolite and ferro-actinolite nephrite is green form (another jade) fibrous is asbestos

grossularite (hessonite) (grossular)

Ca3Al2(SiO4)3 nesosilicate cubic very common member hessonite found in contact metamorphosed limestones

lawsonite

CaAl2Si2O7(OH)2 · H2O sorosilicate, orthorhombic does crystal twinning a lot occurs w BLUESCHIST FACIES it's anorthite but hydrated

anorthite

CaAl2Si2O8

fayalite

Fe2SiO4 iron endmember of olivine nesosilicate/orthosilicate orthorhombic crystal system ahrensite is the Fe 2+ equivalent of ringwoodite (polymorph of fayalite)

almandine

Fe3Al2(SiO4)3 orthosilicate/nesosilicate cubic part of the garnet group forms solid solution w pyrope and spessartine can be found in mica schist

ferrosilite

FeSiO3 single chain inosilicate, orthorhombic part of pyroxene series enstanite (MgSiO3) - ferrosilite IN BETWEEN IS ORTHOPYROXENE idk mostly occurs in conjunction w enstanite pyroxene RIGHT DOWN quad/triangle corner is Fe

biotite

K(Mg,Fe)3AlSi3O10(OH)2 monoclinic phyllosillicate also solid-solution series, layers of lamellae dissolves in both acidic and basic solutions, highest dissolution rates @low pH it's the dark mica

muscovite

KAl2(AlSi3O10)(F,OH)2 or (KF)2(Al2O3)3(SiO2)6(H2O) monoclinic phyllosilicate has mohs hardness 4 perpendicular and 2 parallel found in granite, pegmatite, gneiss, schist it's the light mica

pyrope

Mg3Al2(SiO4)3 orthosilicate/nesosilicate cubic part of the garnet group always displays red coloration in natural samples forms solid solution w almandine and spessartine commonly found in peridotite

serpentine

Mg3Si2O5(OH)4 there are some INTENSE chemical reactions that can happen w/ serpentinite uh NEVER FOUND AS SINGLE CRYSTALS phyllosilicate (microcrystalline and massive) susceptible to acids, pretty soft (2.5-4), light

talc

Mg3Si4O10(OH)2 hydrated magnesium silicate, monoclinic OR triclinic phyllosilicate soapstone is metamorphic rock made of primarily talc there's some chemical reactions might make something later (produced from serpentine + CO2 or dolomite + silica + water or chlorite + quartz) has t-o-t structure/2:1 structure

enstatite

MgSiO3 / Mg2Si2O6 single chain inosilicate, orthorhombic part of pyroxene silicate series enstantite - ferrosilite (FeSiO3) IN BETWEEN IS ORTHOPYROXENE cleavage in 2d at 90 deg common mineral in meteorites pyroxene LEFT DOWN quad/triangle corner as Mg

forsterite

Mg₂SiO₄ magnesium endmember of olivine nesosilicate/orthosilicate orthorhombic crystal system wadsleyite (also orthorhombic, high pressure) -> ringwoodite (cubic, high pressure) are polymorphs

spessartine

Mn3Al2(SiO4)3 nesosilicate cubic occurs most often in granite pegmatite mostly orange

jadeite

NaAlSi2O6 sodium aluminum silicate in monoclinic crystalline form, inosilicate idk where it is on the pyroxene quad/triangle in metamorphic rocks under high pressure/low temp it's albite -> jadeite under high pressure released from serpentine environments

acmite/aegirine

NaFeSi2O6 monoclinic, inosilicate in association w augite (sodium endmember) idk where it is on the pyroxene quad/triangle it's like in every rock i stg

zircon

ZrSiO4 nesosilicate tetragonal system very heavy - 4.6 specific gravity white streak

staurolite

almost always forms short, prismatic crystals usually brown, sometimes forms cruciform twins Fe2Al9O6(SiO4)4(O,OH)2 metamorphosed medium to high grade nesosilicate, monoclinic