Chromate of Lead

This beautiful specimen is from the mine of Berezof, near Catherinbourg, in Siberia. The remarkable richness of colour that it possesses is nearly peculiar to itself, and is very characteristic of the truly orange and scarlet. Specimens so fine as the present are very valuable; this is the best part of a superb one in the Collection of my late friend the Hon. Charles Greville, whose liberality invited me to partake of his matchless cabinet, with the pleasantest freedom, and I am happy to show this as a proof of his generosity, which may be; seen also in British Mineralogy, and as our Government has secured them in the British Museum, I may still hope to find a continuance of such favours.

Although the primitive right angled prism with the short four-sided pyramid is a pretty, somewhat simple and neat figure, easily comprehended, yet the imperfect manner of its being formed, wanting sometimes nearly half, as if the angle were cut off obliquely, makes it so very puzzling, that it has been but little understood.

The upper outline shows the prism and pyramid with a crystal, as found in some of my specimens, and measured from them. The lower outline contains all the modifications I have observed united upon one crystal; and each show the longitudinal striæ on the primitive side or sides of the prism.

There is a yellow pulverulent variety sometimes accompanying these specimens; it does not appear to differ in its composition.

This substance has been found in sufficient abundance to be prepared for the use of the Russian artists; I have two varieties of artificial Chromate of Lead, manufactured from Chromate of Iron, from France, which are very rich; but I do not know that it is less liable to change colour than other preparations of Lead; report, however, speaks favourably of it.