Nonfoliated Textures

Nonfoliated metamorphic rocks do not appear to have any layering. They may however contain long thin crystals, such as toumaline and hornblend that do grow perpendicular to the directed force.

Just as foliated metamorphic rocks, nonfoliated metamorphic rocks are produced through recrystallization, neometamorphis and metasomatism.

During recrystallization, small crystals of one mineral in contact with one another slowly come together to form fewer larger crystals. For example, the sedimentary rock, limestone. Limestone is composed of microscopic crystals of calcite that once formed the shells of marine creatures. When metamorphosed, those tiny crystals are slowly forced together under high pressure and begin to form larger, more visible crystals of calcite found in the metamorphic rock marble.

In other situations, the loss or addition of chemicals results in metasomatism. This can best be seen in the production of anthracite coal, which is almost pure carbon. The parent rock bituminous coal is produced from the aggregation of dead plant material, and anthracite is produced by the loss of the more volatile materials such as nitrogen, oxygen, and methane.

To continue identifying your metamorphic rock select the appropriate grain size from the menu on the left