Oxide of Antimony

Among other specimens in the valuable mineral collection of Mr. Day, was the present, from Endellion Mine in Cornwall, It is a rare mineral, and is also found at Brandsdorf near Freyberg in Hungary, 1 have not hitherto seen crystallized British specimens, nor do I suppose any were ever found. Ours is produced apparently by the gradual decomposition of the Sulphuret; and, where nearest to if, partakes of the fibrous form, and thence passes to somewhat flaky, and finally earthy; and is also softer in proportion as it is further from the gray ore. Sometimes it forms lamina 1 in the cracks or divisions of the gray ore. It is of a light or deeper yellow in proportion to its degree of purity. The specimen has Quartz about it, both opaque and transparent.

This Oxide, which is the Peroxide, is difficultly fusible; but upon Charcoal with the blowpipe it gives out a white smoke and is volatilized, leaving a globule of Lead with the oxide of which it was coloured. It froths with Borax, and partly resumes the gray metallic cast.