Coarse Grained Gabbro Volcanic Rock, 2 Pieces

Each Rock Measures Approx. 1-2 Inches in Length
by American Educational Products

Formed when molten magma has been trapped beneath the Earth’s surface and slowly cools to a holocrystalline mass, Gabbro is highly concentrated within the oceanic crust around the third layer, which constitutes approximately two-thirds of the oceanic crusts volume and is nearly 5km thick.

It is typically coarse grained, with crystals roughly 1mm or greater in size. Finer grained Gabbro does exist, though it is called diabase or microgabbro. Each rock measures approximately 1-2 inches in length. 

Origin: WY