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