Minerals
A large nugget
A Cut Diamond
Quartz
Hexagonal crystals (six sided)
Quartz
Concoidal fracture (like a bottle breaking)
K-spar (Potassium Feldspar
2 planes cleavage-one plane fracture
Fig. 03_02C
Hornblende
Crystals on left- 2 planes of fracture on right
Minerals form rocks!
Polymorphism
2 minerals-same composition-different crystal form
Atomic Structure
Figure 3.5
Ionic Bonding
Gain/Lose (to get 8 in outer shell)
Salt/Halite
Periodic Table
Figure 3.7
Colvalent Bonding
Electron Sharing (to get 8 in outer)
Chlorine
Figure 3.8
Crystal form is expression of internal structure
Salt/Halite in cubes?
Diamonds-all carbon
Strong bonds in all directions create form
Graphite-all carbon
Weak bonds in plane make it soft
Pyrite FeS
Cubic crystals, metallic luster
Quartz
Glassy luster
Use of a streak plate
Moh’s scale of hardness
•Goes up to 10
•Diamond is 10
•Minerals on left
•Tools on right
Figure 3.14
Cleavage
Mica-1 plane
What is this mess!!!!! Relax-its not that hard
Why minerals have certain cleavage?
Cleavage represents internal structure/bonding and defines the mineral
groups
Cleavage in minerals
Mica Group
Feldspar Group
Hornblende Group
Halite
Calcite
Fluorite
Fracture
Concoidal fracture in quartz
K-spar (potassium feldspar)
1 plane fracture (top)-2 planes cleavage
Magnetite
Guess what-its magnetite!
Mineral groups defined by crystal structure
Elements-relative abundance
Minerals on earth-relative abundance
Quartz
Hexagonal Crystals
No cleavage
Conchoidal fracture
Figure 3.26
Quartz
Small amounts of impurities change color
K-spar (potassium feldspar)
Salmon, 2 cleavages at 90 degrees-fracture 1 plane
Plagioclase Feldspar
White, Grey, 2 cleavages at 90 degrees
Fracture 1 plane
Note Striations
Biotite Mica
1 cleavage-sheets
Pyroxene vs. Amphibole Groups
Pyroxene-90 degree
cleavage
Amphibole-60/120
degree cleavage
Amphibole Group
2 cleavages at 60 and 120 degrees
Pyroxene Group
2 cleavages at 90 degrees
Olivine Group
Concoidal fracture-no cleavage
Table 3.2
Non-silicate minerals
Carbonates
Calcite (Ca)
Dolomite (Ca-Mg)
Halides
Fluorite
Halite
Oxides
Hematite (Iron Ore)
Corundum (Ruby-red and Sapphires-blues)
Sulphides
Galena (Lead Ore)
Pyrite (Iron ore)
Sphalerite (Zinc Ore)
Cinnabar (Mercury Ore)
Sulphates
Gypsum (Calcium)
Anhydrite (Calcium)
Near Surface
At Depth
Natives
Diamonds
Precious Stones
Beryl
Emerald
Corundum
Sapphire-blues
Ruby-red