Rocks and minerals

• The science that considers the history of the earth, as recorded in rocks... • Igneous = formed by the cooling and crystallization of magma melted rock • Sedimentary = formed from a

Rocks and Minerals

Science 2201

Grains of sand…

Many ongoing processes constantly change the surface of the globe.

Our Earth is cyclic and restless.

In other words, -everything on the earth

operates in cycles -the surface of the earth

is constantly changing

• The science that considers the

history of the earth, as

recorded in rocks

Basic Structure of the Earth

Earth Structure

• Igneous = formed by the cooling and

crystallization of magma (melted rock)

• Sedimentary = formed from accumulation

of weathered material (sediments)

• Metamorphic = formed from preexisting

rocks that have been transformed (changed)

Igneous, Sedimentary, Metamorphic

 Each type of rock records a different complex past

 Each type of rock can be changed from one form to another and back again

 geologists call these transformations the

“rock cycle”

Rock Cycle

What are Rocks? What are Minerals?

• Rocks

• An aggregate or

mixture of minerals.

• Composition can vary

• Most rocks are

composed of more

• Minerals

• Inorganic chemical elements or

compounds found in the Earth’s crust.

• > 3000 minerals are found in Earth’s crust

Limestone made of Calcite

Granite contains 3 minerals.

• minerals are the building blocks of rocks

• differ in composition and properties

Crystal Form

• Pyrite, Fe2S • Quartz, SiO2

Moh’s Hardness Scale

Cleavage & Fracture

Physical Properties of Minerals

Color and Streak

mineral—corundum (Al2O3)

powdered form, example – hematite

Specific Gravity

• A density measure

• compares weight of a volume of substance

to the weight of the same volume of water

• Example:

– cm 3 pyrite weighs 5X as much as cm 3 water

– cm3 gold weighs 20X more than cm 3 water

Igneous Rock

• formed by cooling & crystallization

of magma

• means “formed by fire”

• make up about 95% of the earth’s crust

• basalt (ocean floor) and granite (continents) are common examples

Igneous Rocks

Texture Silica

Content

Course Granite Diorite Gabbro

Fine Rhyolite Andesite Basalt

Sedimentary Rock

• formed from the weathered material carried by water, wind, or ice

• most common rocks in the upper crust

• cover over 2/3 of the earth’s surface

• sandstone, shale, and limestone

• Inorganic or organic

• Ex-calcite mineral or calcium carbonate

Sedimentary Rocks

Sand Sandstone

• H & P recrystallizes rock

• Igneous limestone to

Metamorphic Rock Origin

• Quartzite from sandstone

Discussion Question for Review

• Chapter 17 Try p 362-363 Discussion

Questions 1-5, 7,9,10

• Chapter 18 Try p 387 Discussion

Questions 1,2,3,5