Sulphate of Lead

These peculiar green Lead Ores have created some confusion among Mineralogist, from their having been considered by several as Molybdates of Lead^*, which, I believe, we have not yet found in this country. I was favoured with the present specimen from Wanlock-head by G. Laing, Esq., who has so often kindly given me occasion to mention him in the course of this work.

The Crystal is a long rectangular prism placed upon one of its sides. Two of its faces, the upper and lower, are primitives; the larger two terminal faces are also primitives, being the sides of a rhomboidal prism; the middle of the three smaller faces is on the acute solid angle, the other two are on the succeeding, or the thus newly made solid angles. We find this to be the same primitive as tab. 153, which upon further examination proves to be also a Sulphate. Its insolubility in hot Nitric Acid diluted, confirms its being a Sulphate, besides other trials, by some of which we are led to suspect a small portion of Muriatic Acid; but we had too small a morsel to try it perfectly^†.

The green hue of the present specimen may depend upon Oxide of Iron, or some foreign ingredient.