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Minerals and RockIntroduction
Brad Hubeny
Minerals: Building blocks of rocks
• By definition a mineral is• Homogenous• Naturally occurring• Inorganic solid• Ordered internal structure of elements• Definite chemical composition
• Rock• A solid aggregate of minerals
Ordered Element Patterns Element Ordering and Crystals
Crystal Growth Structure of minerals
• Polymorphs• Minerals with the same composition
but different crystalline structures• Examples include diamond and
graphite
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Diamond and graphite – polymorphs of carbon
Figure 3.10
How do we ID Minerals?Physical properties!
• Primary diagnostic properties• Determined by observation or
performing a simple test• Several physical properties are used to
identify hand samples of minerals• We’ve looked at these in lab!
Mineral groups• Nearly 4000 minerals have been named• Rock-forming minerals
• Common minerals that make up most of the rocks ofEarth’s crust
• Only a few dozen members• Composed mainly of the 8 elements that make up
over 98% of the continental crust– Classifications based on elements and internal
structure
Elemental abundances in continental crust
Mineral groups
• Silicates• Most important mineral group• Silicon-oxygen tetrahedron
–Fundamental building block–Four oxygen ions surrounding a
much smaller silicon ion
Felsic Minerals (Silicates)
• Silicate minerals rich in silicon andaluminum– Relatively low densities and low
crystallization temperatures– Quartz– Feldspars
• Potassium feldspar• Plagioclase feldspar
– Mica - muscovite
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Mafic Minerals (Silicates)• Silicate minerals rich in iron and
magnesium– Relatively high density and higher
crystallization temperatures– Olivine– Pyroxenes– Amphiboles– Mica - biotite
Nonsilicate Minerals• Usually form at low temperatures
– Carbonates• Calcite - Ca CO3• Dolomite - CaMg(CO3)2
– Evaporite Minerals• Gypsum - CaSO4-2H2O• Halite - NaCl
– Oxides• Hematite
MineralResources
Rocks: Made up of Minerals
Rock Classification
Rock classes are intimately related toeach other through the ROCK CYCLE
IB_01.jpgThe Rock Cycle
