Crystallized Carbonate of Zinc

There has hitherto been some difficulty in distinguishing the two kinds of Calamine, since they both are found sometimes in an earthy and compact form, which in many instances is apt to confound, especially at first sight. The present substance has rather a yellowish, horny, or waxy appearance, but scrapes earthy. It is easily determined when crystallized by its small blunted rhombs, if I may so call them, see the lower outline; or if the crystals be not sufficiently distinct, it may be determined by its fracture, which exposes numerous curved surfaces of small rhombs, having a slight waxy lustre, and not laminated shining spiculæ, as is the case with the Silical Oxide. The Carbonate also effervesces in dilute sulphuric acid. The crystals in this specimen are uncommonly distant; but many of them are so round as to have the appearance of irregular grains rather than crystals, while others are pretty well defined. The gangue is a curious tabular arrangement of crystallized Quartz, the masses of which are cemented together by the Carbonate of Zinc. This specimen is from Flintshire, I was favoured with it by T. Pennant, Esq. The Count de Bournon favoured me with the specimen from which the lower figure was taken.