IGNEOUS ROCKS

Igneous rocks: Latin = ‘fire’ form when molten rock cools and solidifies (crystallizes) into different minerals from magma - Underground.Cools slowly - Solidifies at 700 – 1250o Celsius lava - erupted at Earth's surface. Cools rapidly

Texture The properties and sizes of the various crystals determined by magma's : rate of cooling, and composition

composed of large crystals, Texture = coarse grained Classification of Igneous rocks : Intrusive rocks (or plutonic rocks) - form by slow cooling of magma underground composed of large crystals, Texture = coarse grained crystals had a long time to grow- are large

2. Extrusive rocks (or volcanic rocks) which form at Earth's surface from lava Small crystals, or none at all Cool very fast Texture - fine-grained (aphanitic), - glassy

Felsic/ Mafic Rock Felsic is less dense, lighter in color, usually has a lot of silicon Mafic is dense, darker color, usually has a lot of iron

Granite, Igneous, intrusive, coarse grained, light colored

Gabbro is a dark-colored coarse-grained intrusive igneous rock.

Plutonic rock exposed by weathering

Pumice is a light-colored , felsic, igneous rock Pumice is a light-colored , felsic, igneous rock. It forms through very rapid cooling of lava. The pores are a result of gas trapped in the lava at the time of solidification.

Scoria is a dark-colored, extrusive, igneous rock.

Obsidian - igneous rock Obsidian - igneous rock. Forms when molten rock material cools so rapidly that atoms are unable to arrange themselves into a crystalline structure. Get a volcanic glass with a smooth uniform texture that breaks with a conchoidal fracture Aphanitic

Igneous glassy texture

Basalt is a dark-colored, fine-grained, igneous extrusive rock composed mainly of plagioclase and pyroxene minerals

Igneous Porphyritic texture

Intrusive Rock Formation Plutons – large balloon-shaped formations Batholiths – Huge underground formations Both are made up of Plutonic Rock

Extrusive Rock Formations Remnants of volcanoes or Fissures Dike, Sill, Volcanic neck Solidified lava flows - Rock that FLOATS!! Full of volcanic gas

Summary All igneous rock was once molten!

Classification of Igneous Rocks Extrusive or Intrusive Fine-grained or Coarse–grained, Aphanitic, Porphyritic Fast-forming and Slow-forming Mafic or Felsic

Igneous Rock names to Know Basalt Granite Pumice Scoria Obsidian Diorite Rhyolite Gabbro

Bonifacio, Corsica Photograph by Marc Dozier, Corbis Perched atop 200-foot chalk cliffs, the town of Bonifacio lights up the southern tip of Corsica. The French island is an eruption of granite and magma just 56 miles west of Italy. Its craggy mountains soar to almost 9,000 feet on one coast, while undulating beaches and vineyards line the other.

Homework  Wksht. Quiz - tba