schorl

This is more especially true of chlorite, schorl, hornblende and augite.

The exterior parts of the veins consist of a bluish quartz, very compact, and uniformly containing a great deal of Schorl.

Greisen is closely connected with schorl rock both in its mineralogical composition and in its mode of origin.

In the tourmaline granites prisms of black schorl occur either singly or in stellate groups.

On its northern slope is a vast mass of schorl, the celebrated Roche Rock.