Magma

Composition of Magma• Slushy mix of molten

rock, gases, and mineral crystals

• Elements in magma include:• Oxygen, Silicon,

Aluminum, Iron, Magnesium, Calcium, Potassium, and Sodium.

• Most abundant molecule is Silica.

Formation of Magma

Temperature, Pressure, water content and mineral composition effect magma formation.

In the laboratory most rocks melt between 800-1200 degrees Celsius.

Increasing pressure raises the melting point

Increasing water content lowers the melting point.

http://videos.howstuffworks.com/hsw/17137-whats-inside-the-earth-magma-inside-the-earth-video.htm

Types of magma Basaltic Magma

– Formed in upper mantle, low silica and gas content, low viscosity.

Andesitic Magma– Formed when oceanic crust is subducted into

mantle, medium silica and gas content, intermediate viscosity.

Rhyolitic Magma– Formed when molten rock mixes with silica and

water rich continental crust, high viscosity, large volume of trapped gases.

http://videos.howstuffworks.com/hsw/6186-mountains-of-fire-lava-video.htm

Basaltic Lava

Andesitic Lava

Rhyolitic Lava

Viscosity

Internal resistance to flow. Ex. Honey, liquid soap, motor oil have

higher viscosity than water, vinegar or gasoline.