Rocks and Minerals Metamorphic rocks

Metamorphic Rocks: form as a result of heat, pressure and chemical activity are divided into two groups based on whether they formed from regional or contact metamorphism.

Regional Metamorphic Rocks formed by forces acting over large areas formed at extreme temperature and pressure form at great depths within the earth’s crust form during mountain building due to plate tectonics

Contact Metamorphic Rocks Form at the interface of hot magma and existing rock Forms only locally where the minerals are changed by the extreme heat without actually melting

Characteristics of metamorphic rocks Distortion - a change in the structure of a rock without changing the composition of the rock Banding or zoning - when minerals become concentrated into bands of different colored minerals (pennies in clay)

Increased density - metamorphic rocks are often denser than the rocks they formed from because they are exposed to such high pressure.

Marble - metamorphosed limestone, fizzes with acid Slate - formed from shale, very smooth Quartzite - formed from sandstone, harder than glass Gneiss - usually forms from granite, often banded Schist - exhibits schistosity, often contains mica or garnet.

Marble

Slate

Quartzite

Gneiss

Schist

Mica Schist

Garnet Schist

A Big Pile of Schist

Metaconglomerate