General Lithology:Migmatite Gneiss
Description:A metamorphic rock formed by the action of heat and pressure on a previous igneous or sedimentary rock. Because of its coarse grain-size and banded character it is called a gneiss. This type of gneiss is called migmatite. This signifies that the rock became hot enough to partly melt. The paler bands represent material that was once molten.
Representing:Precambrian basement rock of the Canadian Shield, older than 1 billion years.
Original location:Rochester, Alberta
Estimated mass (tonnes):5