Gabbro boulder from Grant County on a base of scrap steel.  Gabbro forms when magma cools slowly deep beneath the surface, allowing large crystals of white plagioclase and black pyroxene to form. The same magma erupted on the surface cools quickly to form basalt.  This boulder was rounded by the ancient John Day River, then deposited in a terrace as the river deepened its canyon. Thousands of years of weathering eroded the original smooth surface.

HxWxD: 9", 5", 5"  Pivot mount

270 million years old   

Available for Sale:                       $225