Crystallized Carbonate of Zinc

Compact or nearly Amorphous Carbonate of Zinc, like other amorphous subjects, is most difficult to be known by external appearance; the somewhat waxy aspect and bluntish rhomb-like fracture will indicate it, and the more readily when we are well acquainted with the last specimen figured. The present upper specimen is, however, in appearance like confused mammillæ, but with a waxy aspect, and is a greener variety. This substance varies in the intensity of its colour from a bright yellowish green to a dark yellowish brown, and lastly brown, and has seldom more than a waxy transparency. The lower specimen is part of a vein, and appears to have been more or less lined with an ochraccous variety of this substance, layer after layer, on both sides, from the thinness of paper, many times repeated, to that of pasteboard, meeting in the middle, where it is nearly white; the layers are mostly so compressed together as scarcely to show the mammillæ.

Spec. Grav. 4.334.