Silical Oxide of Zinc

These Oxides are so much like some of the Carbonates of Zinc, that upon a superficial examination we should scarcely be able to distinguish them; and perhaps it requires some nice attention to discriminate them even internally, or by the lateral fracture: yet the longitudinally flattish shining fibres are often sufficiently characteristic, and will give a positive distinction, as the Carbonate breaks with rather a scaly fracture. Of the specimens figured in this plate, the white one with long partly diverging transparent spiculæ, covered by an accumulation of bubble-formed almost compact Calamine, is necessary to be known, as it is not a very usual form. The spiculæ in this specimen are not perfect enough to determine their form, but are large enough to become electric by heat, like the more perfectly crystallized specimens. This specimen is from North Wales; and the small bright verditer green one, probably coloured by Copper, is from Wanlockhead. I was favoured with it by Gilbert Laing Meason, Esq. It is a pretty specimen possessing the usual fibrous structure.

These Oxides may be partly discovered by acids, dissolving without effervescence, and the Silex of course remains.