Black Granite Landscape Boulders Granite / Gabbro Central California rock quarry Academy Black Granite, a premium black "granite" rock. This material is exceptional for the quality of the color, hardness and workability. We hand select these black granite boulders from quarry. This rock material is very expensive and not for most budgets. Black granite boulders are really difficult to come by as an affordable landscape material. It is usually easier to use black / gray basalt or other rock materials.
Academy granites vary from almost black to dark gray. The dark gray to black color of the granite allows for excellent contrast between polished and unpolished faces.
The dark gray to black granite at Academy was formed by magma slowly crystallizing as it cooled below the surface of the Earth. While stone from Academy has long been known as 'black granite' in the commercial stone trade, geologically speaking the black stone from the Academy formation is actually a mafic stone and not a true granite. Academy granite is not a true 'black granite' but a gabbro. Gabbros similar to those from Academy cover about 60% of the earth's surface, mostly under the seafloors.
Formed during the Jurassic Age, while dinosaurs roamed the earth, the black to dark gray granites of the Academy formation were once molten magma at the base of an ancient volcano. The magma cooled and crystallized into the black granite (gabbro).
Academy granite was named for the town of Academy in Fresno County, California where this black granite was first quarried. Granite has been quarried there since the late 1800's and was used even earlier by the Yakut tribe for stone tools
