MINERALSTYPES OF BONDING

INTERMOLECULAR BONDING

HYDROGEN BONDINGOccurs primarily between water molecules due to polarity.

VAN DER WAALS BONDINGOccurs when all electrons end up on one side of atoms and

a charge develops.

Carbon in Graphite

MINERALSDETERMINANTS IN MINERAL FORMATION

The minerals that form in the Earth are dependent upon:abundance of available elements at time of

formation.size of the elements.temperature and pressure at time of formation.

Most Abundant Elements in Earth’s Continental CrustELEMENT PROPORTION OF CRUST’S WEIGHT (%)

Oxygen (O) 45.20Silicon (Si) 27.20Aluminum (Al) 8.00Iron (Fe) 5.80Calcium (Ca) 5.06Magnesium (Mg) 2.77Sodium (Na) 2.32Potassium (K) 1.68

98.03All Other Elements 1.97Total 100 %

Most minerals in Crust are oxygen-silicon based compounds.

Most Abundant Elements in Entire Earth

ELEMENT PROPORTION OF EARTH’S WEIGHT (%)

Iron (Fe) 34.80Oxygen (O) 29.30Silicon (Si) 14.70Magnesium (Mg) 11.30Sulfur (S) 3.30Nickel (Ni) 2.40Calcium (Ca) 1.40Aluminum (Al) 1.40

98.40All Other Elements 1.60Total 100 %

Most minerals in Upper Mantle are oxygen-silicon-magnesium-iron compounds.

MINERALS

Size of elements is also a factor in mineral formation.

Positive ions are usually smaller than negative ions.

Smaller positive ions tend to fit in spaces betweenlarger negative ions.

MINERALSCOMMON MINERAL GROUPS

Rock forming minerals compose the most common rocks in the Earth’s crust and mantle.

Seven basic mineral groups.

Most of the minerals in the crust and mantle are silicates.

Elements are generally solitary (homogeneous).Do not combine with other elements in nature.

Gold (Au)Silver (Ag)Platinum (Pt)Diamond (C)Graphite (C)Sulfur (S)Copper (Cu)

MINERALSNONSILICATE MINERALSNATIVE ELEMENTS

Copper

Silver

Gold

MINERALSNONSILICATE MINERALSCARBONATES

Carbonate ion (CO32-) is prominent in minerals.

Has -2 charge.Combines readily with positive ions.Bonds generally weak.Minerals are soft (3-4).Minerals are soluble in acidic water.

Leads to cave development.

Calcite (CaCO3)Dolomite (CaMg(CO3)2)

DOLOMITE

CALCITE

OOLITICHEMATITE

MINERALSNONSILICATE MINERALSOXIDESProduced when negative OXYGEN (O2-) ions combine with

positive metallic ions.

Specular hematite (Fe2O3)Oolitic hematite (Fe2O3)Magnetite (Fe3O4)Corundum (Al2O3)

MAGNETITE

SPECULARHEMATITE

CORUNDUM

MINERALSNONSILICATE MINERALSHYDROXIDESProduced when negative HYDROXIDE (OH-) ions combine with

positive metallic ions.

Limonite (FeOOH)Bauxite

BAUXITE

LIMONITE

Produced when negative SULFUR (S2-) ions combine withpositive metallic ions.

Oxygen’s ugly sibling.

Pyrite (FeS2)Chalcopyrite (Cu,FeS2)Galena (PbS)Sphalerite (Zn,Fe)S

MINERALSNONSILICATE MINERALSSULFIDES

PYRITE

GALENA

CHALCOPYRITE SPHALERITE

MINERALSNONSILICATE MINERALSSULFATES

Produced when negative SULFATE (SO42-) ions combine with

positive metallic ions.

Gypsum (CaSO4 . H2O)

MINERALSNONSILICATE MINERALSHALIDES

FLUORITE

HALITE

Produced when negative HALIDE (F, Cl, Br, I) ions combine with positive metallic ions.

Halite (NaCl)Fluorite (CaF2)

MINERALSSILICATES AND THEIR STRUCTURE

Silicate minerals:Constitute 90% of the weight of the crust.Are a dominant constituent in igneous, metamorphic,

and sedimentary rocks.

Silicate crystal structure is a repeatedgrouping of four oxygen ionsand one silicon ion.

SiO4

Produces a silicon-oxygen TETRAHEDRON.

MINERALSSILICATES AND THEIR STRUCTURE

Silicon tetrahedron (SiO4) produced a -4 charge.Allows bonding with other elements or other tetrahedra.

Silicon-Oxygen RatioNumber of O ions shared by tetrahedra.

A tetrahedron that sharesnone of its oxygen hasSi:O ratio of 1-4.

A tetrahedron that sharesall of its oxygen hasSi:O ratio of 1-2.

MINERALSFIVE PRINCIPLE SILICATE STRUCTURES

OLIVINE

GARNETSTAUROLITE

OLIVINE

1. INDEPENDENT TETRAHEDRA - ISLAND SILICATES

Independent tetrahedra have -4 charge.Tetrahedra bond with positive ions.Share no oxygen ions.Generally are hard minerals.Strong ionic bonding exists.Si:O ratio = 1:4

MINERALS2. SINGLE CHAIN SILICATES

AUGITE

Silica tetrahedra share two corner oxygen ions.Bonds with positive ions.Bonds within chains are strong.Bonds between chains are weak.

Minerals cleave parallel to chains.Si:O ratio = 1:3

Acquires Ca2+, Mg2+, Fe2+ to neutralize ionic charges.

MINERALS

ACTINOLITE HORNBLENDE

3. DOUBLE CHAIN SILICATES

Tetrahedra share two corners in linear chain and some share athird oxygen with tetrahedra in neighboring chain.

Shared oxygen ions bond chains together.Si:O ratio = 1:2.75Generally accept Na+, Ca2+, Mg2+, Fe2+, Al3+.

4. SHEET SILICATES

MINERALS

BIOTITE

MUSCOVITE

Tetrahedra share 3 basal oxygen ions.Produces a sheet.Fourth oxygen bonds with positive ions.This bonds the sheet together.Bonds between the sheets are extremely weak.Si:O ratio = 1:2.5

MINERALS5. FRAMEWORK SILICATES

Tetrahedra share all four oxygen ionswith adjacent tetrahedra.

Produces three-dimensional framework.Si:O ratio = 1:2Quartz and relatives and Feldspars two most abundant mineral

groups in the Earth’s crust.

QUARTZ (SiO2)

FELDSPAR

Two groups:Plagioclase feldspar

contains Na and CaOrthoclase feldspar

contains KAll have 2 directions of cleavage at 90.Most common mineral group in Earth’s crust

Has extremely strong bondsHardest of the common rock-forming mineralsHas no cleavage, conchoidal fractureQuartz and relatives second most abundant mineral group

in Earth’s crust.