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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.
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