Minerals to Memorize

Native minerals

Elements found in their pure form without chemical combination with other elements.

Halides

Cl, Br, F,

Oxides

O

Sulfates

SO₄

Sulfides

S

Phosphates

PO₄

Carbonates

CO₃

Silicates

SiO₂

Apatite

phosphate: Ca₅(PO₄)₃(OH,F,Cl)

Aragonite

carbonate: CaCO₃

Bornite

sulfide: Cu₅FeS₄

Calcite

carbonate CaCO₃

Chalcocite

sulfide: Cu₂S

Chalcopyrite

sulfide: CuFeS₂

Cinnabar

sulfide: HgS

Corundum

oxide: Al₂O₃

Crocoite

oxide: PbCrO₄.

Diamond

native element: C

Fluorite

halide: CaF₂

Galena

sulfide: PbS

Graphite

native element: C

Gypsum

sulfate: CaSO₄-2H₂O

Halite

halide: NaCl

Hematite

oxide: Fe₂O₃.

Magnesite

carbonate: MgCO₃

Magnetite

oxide: Fe₃O₄.

Malachite

carbonate: Cu₂CO₃(OH)₂

Molybdenite

sulfide: MoS₂

Pyrite

sulfide: FeS2

Rhodochrosite

carbonate: MnCO₃

Rutile

oxide: TiO₂

Sulfur

native: S

Siderite

carbonate: FeCO₃

Sphalerite

sulfide: ZnS

Stibnite

sulfide: Sb₂S₃

Topaz

silicate: Al₂SiO₄(F, OH)₂

Orthosilicates

Silicate minerals in which the silicate tetrahedron is independent.

General formula for olivine

orthosilicates: (Mg, Fe)₂SiO₄

General formula for garnet

orthosilicates: X₃Y₂(SiO₄)₃

Single chain silicates

Silicates where tetrahedra link in chains, such as pyroxenes.

General pyroxene formula

single chain silicates: XYZ₂O₆.

Double chain silicates

Silicates where tetrahedra link in double chains, such as amphiboles.

General amphibole formula

double chain silicates: A_0-1B₂C₅T₈0₂₂W₂.

Sheet silicates

Silicate minerals with layered structures, such as micas and clays.

Framework silicates

Silicate minerals with interconnected frameworks of tetrahedra, such as quartz and feldspar.

Almandine

garnet, orthosilicate: Fe3Al2(SiO4)3

Andalusite

orthosilicate: Al2SiO5

Fayalite

orthosilicate: Fe2SiO4

Forsterite

orthosilicate: Mg2SiO4

Grossular

garnet, orthosilicate: Ca3Al2(SiO4)3

Kyanite

orthosilicate: Al2SiO5

Pyrope

garnet, orthosilicate: Mg3Al2(SiO4)3

Sillimanite

orthosilicate: Al2SiO5

Spessartine

garnet, orthosilicate: Mn3Al2(SiO4)3

Topaz

orthosilicate: Al2SiO4(F, OH)2

Zircon

orthosilicate: ZrSiO4

General formula for pyroxene

single chain silicates: XYZ₂O₆

Distinguishing orthopyroxene and clinopyroxene

Orthopyroxene (e.g., enstatite and ferrosilite) typically exhibits a single prism crystal habit and has a higher Mg/Fe ratio, while clinopyroxene (e.g., diopside and augite) shows a more complex crystal structure with two distinct cleavage angles and a greater variation in composition.

Enstatite

single chain silicate: Mg₂Si₂O₆

Ferrosilite

single chain silicate: Fe₂Si₂O₆

Hedenbergite

single chain silicate: CaFeSi₂O₆

Diopside

single chain silicate: CaMgSi₂O₆

Augite

single chain silicate: (Ca,Na)(Mg,Fe,Al)(Al,Si)₂O₆.

General amphibole formula

double chain silicates: A_0-1B₂C₅T₈0₂₂W₂

Tremolite

double chain silicates: Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂

Actinolite

double chain silicates: Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂

Hornblende

double chain silicates: (Na, K)_0-1Ca₂(Mg, Fe, Al)₅(Si,Al)₈O₂₂(OH)₂

Glaucophane

double chain silicates: Na₂Mg₃Al₂Si₈O₂₂(OH)₂

Sheet silicates

Silicate minerals with layered structures, such as micas and clays.

Kaolinite

sheet silicate: Al2(Si2O5)(OH)4.

Serpentine

sheet silicate: Mg3(Si2O5)(OH)4.

Talc

sheet silicate: Mg3(Si4O10)(OH)2.

Muscovite

sheet silicate: KAl2(AlSi3O10)(OH)2.

Biotite

sheet silicate: K(Mg,Fe)3(AlSi3O10)(OH)2.

Chlorite

sheet silicate: Mg3([Si,Al]4O10)(OH)2 . (Mg,Al)3(OH)6.

Classification of sheet silicates

Classified as TOT (Tetrahedral-Octahedral Tetrahedral), TOT+C (Tetrahedral-Octahedral Tetrahedral + Cation), and TOT+O (Tetrahedral-Octahedral Tetrahedral + Octahedral).

Dioctahderal vs Trioctahedral

Dioctahderal has two octahedral cations per unit cell while trioctahedral has three octahedral cations per unit cell.

Framework silicates

Silicate minerals with interconnected frameworks of tetrahedra, such as quartz and feldspar.

Quartz

framework silicate: SiO₂

Chrysotile

framework silicate: SiO₂

Opal

framework silicate: SiO₂^.nH₂O

Plagioclase feldspar

framework silicate: CaAl₂Si₂O₈ to NaAlSi₃O₈

Alkali feldspar

framework silicate: NaAlSi₃O₈ to KAlSi₃O₈