Chapter 5: Igneous Rocks

Characteristics that make igneous rocks useful as building materials

1) Strength - The interlocking grain textures of igneous rocks make them strong. 2) Durability - Many of the minerals present in igneous rocks are resistance to weathering. 3) Beauty

Vesicular Texture

A rock texture characterized by containing vesicles, or holes, formed by gas bubbles.

Porphyritic Texture

A rock that has grains of two different sizes of the same mineral

Intrusive Rock

Course-grained igneous rock that is formed when molten rock cools slowly and solidifies beneath the Earth's crust.

Extrusive Rock

Fine-grained igneous rock that is formed when molten rock cools quickly and solidifies on Earth's surface.

Pegmatite

Igneous rock with extremely large-grained minerals that can contain rare ores such as lithium and beryllium.

Bowen's Reaction Series

Illustrates the relationship between cooling magma and mineral formation..

Igneous Rock

Intrusive or extrusive rock formed from the cooling and crystallization of magma or lava.

Veins

Layers of valuable ore deposits that occur between layers of igneous rock intrusions.

Granitic Rock

Light-colored, intrusive igneous rock that has high silica content.

Lava

Magma that flows out onto Earth's surface through cracks or openings in the crust.

Magma

Molten rock below Earth's surface.

Kimberlite

Rare, ultramafic rock that can contain diamonds and other minerals formed only under very high pressures.

Basaltic Rock

Rock that is dark colored, has lower silica contents, and is rich in iron and magnesium. example Gabbro

Factors a rocks melting point

Temperature, Pressure, Water Content, and Mineral Content

Fractional Crystallization

The process in which different minerals crystallize from magma at different temperatures, removing elements from magma.

Partial Melting

The process in which different minerals melt into magma at different temperatures, changing its composition.

Different minerals melt and crystallize

at different temperatures

ultramafic rock

rock such as periodotite, which as low silica content and very high levels of iron and magnesium

Most abundant compound found in magma

silica