List of 10 minerals (groups) you really want to know to be

people

• Quartz, Olivine, Amphibole, Pyroxene, Feldspars, Garnet, Staurolith, Aluminosilicates, Micas, Calcite

Chemical classes of mineralsChemical classes of minerals

Silicates – contain O and SiSilicates – contain O and SiCarbonates – contain C and OCarbonates – contain C and OOxides – contain O and Oxides – contain O and metallic cations metallic cationsSulfides – contain S and Sulfides – contain S and metallic cations metallic cationsSulfates – contain SO4 and Sulfates – contain SO4 and

metallic cations metallic cations

Rock-forming mineralsRock-forming minerals

Chemical classes - Chemical classes - continuedcontinued

Halides – contain Cl, F, I, or Halides – contain Cl, F, I, or Br Br

Hydroxides – contain OHHydroxides – contain OHNative elements – masses of Native elements – masses of all the same element all the same element metallically bonded metallically bonded

Rock-forming mineralsRock-forming minerals

Silicate ion (SiO44–)

Oxygen ions(O2–) Silicon ion

(Si4+)

The silicate ion forms tetrahedra.

Quartzstructure

Rock-forming mineralsRock-forming minerals

Formation of silicate mineralsFormation of silicate minerals

Rock-forming mineralsRock-forming minerals

Isolated silica tetrahedraIsolated silica tetrahedrahave isolated [SiO4]have isolated [SiO4]4−4− tetrahedra that are connected only by interstitial tetrahedra that are connected only by interstitial cations.cations.

Single-chain linkagesSingle-chain linkageshave interlocking chains of silicate tetrahedra with SiOhave interlocking chains of silicate tetrahedra with SiO33, 1:3 ratio, , 1:3 ratio,

Double-chain linkagesDouble-chain linkageslike above but Silike above but Si44OO1111, 4:11 ratio, for double chains., 4:11 ratio, for double chains.

Sheet linkagesSheet linkagesparallel sheets of silicate tetrahedra with Siparallel sheets of silicate tetrahedra with Si22OO55 or a 2:5 ratio. or a 2:5 ratio.

FrameworksFrameworkshave a three-dimensional framework of silicate tetrahedra with SiOhave a three-dimensional framework of silicate tetrahedra with SiO22 or a or a

1:2 ratio.1:2 ratio.

Mineral Chemical formula

Cleavage planesand number of

cleavage directionsSilicate

structure Specimen

1 plane Isolatedtetrahedra

Olivine (Mg, Fe)2SiO4

Isolated tetrahedra (soro- and nesosilicates)

Olivine group: forsterite-fayalite solid solution

Mineral Chemical formula

Cleavage planesand number of

cleavage directionsSilicate

structure Specimen

1 plane Isolatedtetrahedra

2 planes at 90°Single chains

Olivine

Pyroxene

(Mg, Fe)2SiO4

(Mg, Fe)SiO3

Mineral Chemical formula

Cleavage planesand number of

cleavage directionsSilicate

structure Specimen

1 plane Isolatedtetrahedra

2 planes at 90°Single chains

2 planes at 60°and 120° Double chains

Olivine

Pyroxene

Amphibole

(Mg, Fe)2SiO4

(Mg, Fe)SiO3

Ca2(Mg, Fe)5Si8O22(OH)2

Fig. 2.17

Fig. 3.19

Single chains of tetrahedra

Pyroxene group

Fig. 3.11

Double chains of tetrahedra

Amphibole group

Mineral Chemical formula

Cleavage planesand number of

cleavage directionsSilicate

structure Specimen

1 plane Isolatedtetrahedra

2 planes at 90°Single chains

2 planes at 60°and 120° Double chains

1 plane Sheets

Olivine

Pyroxene

Amphibole

Micas

(Mg, Fe)2SiO4

(Mg, Fe)SiO3

Ca2(Mg, Fe)5Si8O22(OH)2

Muscovite:KAl2(AlSi3O10)(OH)2

Biotite:K(Mg, Fe)3AlSi3O10(OH)2

Sheets of tetrahedra (phyllosilicates)

Mica group

chrysotile

Mineral Chemical formula

Cleavage planesand number of

cleavage directionsSilicate

structure Specimen

1 plane Isolatedtetrahedra

2 planes at 90°Single chains

2 planes at 60°and 120° Double chains

1 plane Sheets

Olivine

Pyroxene

Amphibole

Micas

Feldspars

2 planes at 90° Three-dimensionalframework

(Mg, Fe)2SiO4

(Mg, Fe)SiO3

Ca2(Mg, Fe)5Si8O22(OH)2

Muscovite:KAl2(AlSi3O10)(OH)2

Biotite:K(Mg, Fe)3AlSi3O10(OH)2

Orthoclase feldspar:KAlSi3O8

Plagioclase feldspar: (Ca, Na) AlSi3O8

3-D frameworks of tetrahedra (tectosilicates)

Feldspar group

Feldspars

Some minerals contain water

• E.g., Amphiboles, Chlorite, Serpentine

• Water plays a crucial role in plate tectonic.

Halides• Fluorite CaF2

• Halite NaCl• Sylvite KCl

halite x 2

fluorite x 2

sylvite

Carbonates• Second most abundant group in the Earth’s

crust

• Major component of limestone, marble, carbonatites

• Three major minerals:Calcite: CaCO3

Aragonite: CaCO3

Dolomite: (Ca,Mg)CO3

calcite

aragonite x 2

Fig. 3.12

Aragonite is the high-pressure polymorph of calcite, but it is also found in shells, hot springs, and cave deposits

Tem

per

atu

re (

C)

70% of bone is made of “hydroxyapatite:” apatite, calcite, fluorite, calcium hydroxide;90% of tooth enamel consists of this

TEM image showing apatite nano-crystals in a well-preserved dinosaur bone. Huifang Xu, Madison

Phosphates

Apatite: Ca5(PO4)3S

apatite on calcite

SulfatesGypsum CaSO4·2H2O (anhydrite: no H2O) Barite BaSO4

gypsum, gypsum, growing in mud

anhydrite

barite

SulfidesPyrite FeS2

Galena PbS

Oxides and hydroxidesMagnetite Fe3O4

HematiteFe2O3

Corundum Al2O3

magnetite

hematite x 2

corundum x 2

Pre

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bars

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