Rocks and MineralsRocks and Minerals

• Atoms, Elements, Isotopes, Ions, and Compounds

• Minerals–General

• Types of Minerals

• Rocks

Minerals- the building blocksMinerals- the building blocks

• Atomic Structure

• Elements and Isotopes

• Ions

• Compounds

Rocks and MineralsRocks and Minerals

• Minerals Defined

• Identifying Characteristics of Minerals

• Other Physical Properties of Minerals

Halite Crystal

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.

Galena

Source: Photograph © The McGraw-Hill Companies, Inc./Doug Sherman, photographer.

Fluorite

Source: Photograph © The McGraw-Hill Companies, Inc./Doug Sherman, photographer.

Halite

Source: Photograph © The McGraw-Hill Companies, Inc./Doug Sherman, photographer.

Definition of a MineralDefinition of a Mineral

“A naturally occurring, inorganic, solid element or compound with a definite chemical composition and a regular internal crystal structure.”

Mineral CharacteristicsMineral Characteristics

• Chemical composition– Diamond = graphite (both are pure carbon)

• Crystal structure– Diamond ≠ graphite

Cubic Structure of Halite

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.

Mineral PropertiesMineral Properties

• Hardness (Mohs hardness scale)– See appendix C

• Cleavage (how it breaks- atomic scale)

• Luster- the surface ‘sheen’

• Color is not a good property for i.d.– Corundum (Al2O3)

Minerals: two groupsMinerals: two groups

• Silicates (Si + O ± other elements)– All built with ‘silicon tetrahedra’– 4 O atoms, 1 Si atom, 4- charge– Quartz, feldspars– Olivine (peridot) ferromagnesian (Fe, Mg)– Asbestos– Micas– Clays (tropical weathering)

Minerals: non-silicatesMinerals: non-silicates

• Nonsilicates Example– Carbonates (CO3): calcite

– Sulfates (SO4): gypsum

– Sulfides (metal + S): pyrite– Oxides (metal + O): hematite– Hydroxides (metal + OH): gibbsite– Halides (metal + halide): salt (halite)– Native elements Au, Ag, Pt, Cu, C

RocksRocks

• The Rock Cycle

• Igneous Rocks

• Sediments and Sedimentary Rocks

• Metamorphic Rocks

• The Rock Cycle Revisited

Definition of a RockDefinition of a Rock

• A solid, cohesive aggregate of one or more minerals or mineral materials

• Important for construction

• Geologic history

The Rock CycleThe Rock Cycle

• Earth as a constantly changing system

• Plate tectonics

• 3 types of rocks on Earth– Igneous– Sedimentary– Metamorphic

The Rock CycleThe Rock Cycle

• Igneous Rocks– Formed by the crystallization of magma– Usually made up of silicate minerals– Plutonic: solidified inside Earth (granite)– Volcanic: solidified on Earths surface (lava)

Granite, a Plutonic Rock

Source: Courtesy of Carla W. Montgomery.

Obsidian, Volcanic Glass

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.

Basalt, a Volcanic Rock

Source:Courtesy of Carla W. Montgomery.

Porphyry, an Igneous Rock

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.

The Rock CycleThe Rock Cycle

• Sedimentary Rocks– Chemical precipitation

• Limestone (carbonate), chert

– Clastic sedimentation• Sandstone, shale, conglomerate

Limestone

Source: Photograph by I.J. Witkind, USGS Photo Library, Denver, CO.

Shale

Source: Photograph © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.

Sandstone

Source: Photograph © The McGraw-Hill Companies, Inc./Doug Sherman, photographer.

Conglomerate

Source: Courtesy of Carla W. Montgomery.

The Rock CycleThe Rock Cycle

• Metamorphic Rocks– Changed form– Heat, pressure, fluids– Metamorphism: contact vs. regional

Marble

Source: Courtesy of Carla W. Montgomery.

Quartzite

Source: © The McGraw-Hill Companies, Inc./Bob Coyle, photographer.

Schist

Source: Courtesy of Carla W. Montgomery.

Gneiss

Figure 2.12D

2-19 Source: Courtesy of Carla W. Montgomery.