Datholite

Datholite (Gr. dathos, 'turbid'), a mineral, colourless or inclining to grayish, greenish, white, or yellowish-gray colour, occurring both massive and crystallised in rhombic prisms, the edges and angles of which are commonly replaced by planes. It is composed of boracic acid, silica, and lime, with a little water. It has been found both in schistose and crystalline igneous rocks; and occurs near Edinburgh, in Norway, Italy, Connecticut, &c.