Varpaisjärven musta diabaasi, PG Black

Black diabase from Varpaisjärvi, PG Black.

Diabase is a hypabyssal rock of the same mineral composition as gabbro. The diabases are black in colour and slightly finer-grained than the diorites or gabbros. Being non-oriented rocks, the diabases have their mineral grains densely overlapping, which makes them especially strong and tough.