MINERALS
TYPES OF BONDING
INTERMOLECULAR BONDING
HYDROGEN BONDING
Occurs primarily between water molecules due to polarity.
VAN DER WAALS BONDING
Occurs when all electrons end up on one side of atoms and
a charge develops.
Carbon in Graphite
MINERALS
DETERMINANTS 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 Crust
ELEMENT
PROPORTION OF CRUST’S WEIGHT (%)
Oxygen (O)
Silicon (Si)
Aluminum (Al)
Iron (Fe)
Calcium (Ca)
Magnesium (Mg)
Sodium (Na)
Potassium (K)
All Other Elements
Total
45.20
27.20
8.00
5.80
5.06
2.77
2.32
1.68
98.03
1.97
100 %
Most minerals in Crust are oxygen-silicon based compounds.
Most Abundant Elements in Entire Earth
ELEMENT
PROPORTION OF EARTH’S WEIGHT (%)
Iron (Fe)
Oxygen (O)
Silicon (Si)
Magnesium (Mg)
Sulfur (S)
Nickel (Ni)
Calcium (Ca)
Aluminum (Al)
34.80
29.30
14.70
11.30
3.30
2.40
1.40
1.40
98.40
All Other Elements
1.60
Total
100 %
Most minerals in Upper Mantle are oxygen-silicon-magnesiumiron 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 between
larger negative ions.
MINERALS
COMMON 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.
MINERALS
NONSILICATE MINERALS
NATIVE ELEMENTS
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)
Gold
Copper
Silver
MINERALS
NONSILICATE MINERALS
CARBONATES
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
MINERALS
NONSILICATE MINERALS
OXIDES
CORUNDUM
Produced when negative OXYGEN (O2-) ions combine with
positive metallic ions.
Specular hematite (Fe2O3)
Oolitic hematite (Fe2O3)
Magnetite (Fe3O4)
Corundum (Al2O3)
SPECULAR
HEMATITE
OOLITIC
HEMATITE
MAGNETITE
MINERALS
NONSILICATE MINERALS
HYDROXIDES
Produced when negative HYDROXIDE (OH-) ions combine with
positive metallic ions.
Limonite (FeOOH)
Bauxite
LIMONITE
BAUXITE
MINERALS
NONSILICATE MINERALS
SULFIDES
Produced when negative SULFUR (S2-) ions combine with
positive metallic ions.
PYRITE
Oxygen’s ugly sibling.
Pyrite (FeS2)
Chalcopyrite (Cu,FeS2)
Galena (PbS)
Sphalerite (Zn,Fe)S
GALENA
CHALCOPYRITE
SPHALERITE
MINERALS
NONSILICATE MINERALS
SULFATES
Produced when negative SULFATE (SO42-) ions combine with
positive metallic ions.
Gypsum (CaSO4 . H2O)
MINERALS
NONSILICATE MINERALS
HALIDES
Produced when negative HALIDE (F, Cl, Br, I) ions combine
with positive metallic ions.
Halite (NaCl)
Fluorite (CaF2)
HALITE
FLUORITE
MINERALS
SILICATES 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 repeated
grouping of four oxygen ions
and one silicon ion.
SiO4
Produces a silicon-oxygen
TETRAHEDRON.
MINERALS
SILICATES AND THEIR STRUCTURE
Silicon tetrahedron (SiO4) produced a -4 charge.
Allows bonding with other elements or other tetrahedra.
Silicon-Oxygen Ratio
Number of O ions shared by tetrahedra.
A tetrahedron that shares
none of its oxygen has
Si:O ratio of 1-4.
A tetrahedron that shares
all of its oxygen has
Si:O ratio of 1-2.
MINERALS
FIVE PRINCIPLE SILICATE STRUCTURES
1. INDEPENDENT TETRAHEDRA - ISLAND SILICATES
Independent tetrahedra have -4 charge.
Tetrahedra bond with positive ions.
Share no oxygen ions.
Generally are hard minerals.
OLIVINE
Strong ionic bonding exists.
Si:O ratio = 1:4
STAUROLITE
GARNET
MINERALS
2. SINGLE CHAIN SILICATES
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
AUGITE
Acquires Ca2+, Mg2+, Fe2+ to neutralize ionic charges.
MINERALS
3. DOUBLE CHAIN SILICATES
Tetrahedra share two corners in linear chain and some share a
third oxygen with tetrahedra in neighboring chain.
Shared oxygen ions bond chains together.
Si:O ratio = 1:2.75
Generally accept Na+, Ca2+, Mg2+, Fe2+, Al3+.
ACTINOLITE
HORNBLENDE
MINERALS
4. SHEET SILICATES
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
MUSCOVITE
BIOTITE
MINERALS
5. FRAMEWORK SILICATES
Tetrahedra share all four oxygen ions
with adjacent tetrahedra.
Produces three-dimensional framework.
Si:O ratio = 1:2
Quartz and relatives and Feldspars two most abundant mineral
groups in the Earth’s crust.
FELDSPAR
Two groups:
Plagioclase feldspar
contains Na and Ca
Orthoclase feldspar
contains K
All have 2 directions of cleavage at 90.
Most common mineral group in Earth’s crust
QUARTZ (SiO2)
Has extremely strong bonds
Hardest of the common rock-forming minerals
Has no cleavage, conchoidal fracture
Quartz and relatives second most abundant mineral group
in Earth’s crust.