Rocks and Minerals Rocks are made of minerals

Rocks and Minerals � Rocks are made of minerals, which are solid nonliving substances formed by natural processes in or on the Earth.

�Types of minerals �Metallic minerals = tin, iron, copper, silver, gold, etc. �Nonmetallic minerals �Gemstones = diamonds, rubies, emeralds, etc �Rock-forming minerals = quartz, mica, hornblende

3 Types of rocks Igneous Sedimentary Metamorphic

�Igneous Rock, formed from cooled lava or magma �Intrusive = cooled magma trapped in underground cracks and openings �May take thousands of years to cool �Crystals have time to grow �Coarse texture

Igneous Intrusions

Intrusive Igneous Rock: Pegmatite

Extrusive = cooled lava (above ground) Cooled very quickly Very small or no crystals, may be glassy or full of holes

Extrusive Igneous Rock : Obsidian

Sedimentary Rock, formed from broken bits of rocks, minerals, living things, or dissolved minerals

Compaction: sediments build up in layers, bottom layers turned to rock by pressure Cementation: coarse sediments held together by pieces of rocks or minerals

Plant and animal remains change chemically and harden Sediments dissolved in water crystallize as water evaporates

�Types �Detrital or Clastic, from broken bits of rocks and minerals �Chemical, from minerals dissolved in water �Organic, from substances that were once alive

How Coal Forms

White Sandstone

Conglomerate

�Metamorphic rock, rock changed from one type to another by great heat, pressure, or chemical change. �Happens mostly underground (high heat and pressure)

�Types �Foliated rock, minerals arranged in layers as they recrystallize or are flattened under pressure �Nonfoliated rock, not formed in layers

Foliated: Hornblende gneiss

Nonfoliated: Marble