ORBICULAR GRANITE SPECIMENS

Orbicular granite is the name given to an unusual kind of plutonic granite formation. The granite forms as orbicules, spherical formations of concentric bands of minerals around a grain of material serving as a nucleus. They form as fluid-rich dioritic magma cools quickly around these nucleus grains. Some deposits' orbicules show gravitational deformation: they are deformed by each other, seemingly by stacking as they precipitated out of magma.