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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