Igneous Rocks Igneous Rocks Igneous rocks form when

Igneous Rocks

Igneous Rocks • Igneous rocks form when molten rock cools and hardens.

Magma or Lava? • Magma: molten rock under ground • Lava: Molten rock above ground

2 Types of Igneous Rocks Extrusive- cool and harden at the surface - they cool fast so they don’t have time to form big mineral crystals Intrusive- cool and harden under the earth’s surface crystals -they cool slow so they form bigger mineral

Igneous rock formation

Igneous rock formation

Basalt • Color- black • Made of- lava • How formed-extrusive (cooling lava) • Otheraa- rough lava pahoehoe- smooth lava

Obsidian • • Color- black (clear) Made of- volcanic glass How formed-extrusive, cools VERY fast Other – arrowheads, sharp

Red Pumice • • Color- red Made of- frothy volcanic lava How formed- extrusive Other- bubbles (vesicles), very light weight

Black Pumice • • Color- black Made of- frothy volcanic lava How formed- extrusive Other- bubbles (vesicles), very light weight

White Pumice • • Color- grey white Made of- frothy volcanic lava How formed- extrusive Other- bubbles (vesicles), floats

Granite • Color- red, white, black, grey, etc… • Made of- quartz, many other minerals • How formed- intrusive, far under ground so crystals can slowly grow bigger • Other- large crystals

Rhyolite • • Color- grey, pinkish Made of – quartz and other minerals How formed- intrusive Other- small crystals

Igneous Rocks Info Sheets 7 Igneous Rocks Name, picture, extrusive or intrusive? , other characteristics 1. Basalt extrusive aa- rough pahoehoe-smooth 2. 3. Picture on page 83 - labelled - colored 4. 5. 6. 7. - intrusive: cool underground slow : big crystals - extrusive: cool aboveground fast : small or no crystals