Phosphate of Copper

Tab. 54 Exotic Mineralogy, shows an inferior specimen of this ore as a great rarity; the time has however arrived that far better are discovered in our own country, the description and figure of which will, 1 trust, be received with satisfaction, although before noticed as foreign.^* Those fine specimens from Cornwall are truly remarkable, as well as their similarity to the Arseniates for which they have been taken: yet so precise was nature in producing them, that 1 don't know a single specimen having been found till lately, and, therefore, the Arseniates figured in this work were not intermixed with them.

It is, perhaps, difficult to know by mere external aspect, yet by a little practice in comparison, we may distinguish it by its colour and superior lustre, and next the blowpipe with Charcoal may add to the certainty, by the want of the garlick-scented fumes and by the grey scoria produced, differing from the Arseniate, which produers fumes and a globule of nearly pure Copper; analysis settling it most perfectly, and probably with the same result as the foreign ones.

The upper specimen from Gunnis or Gunner’s lake mine possesses much variety, the darker parts are the phosphate, which is shown with a larger character in the lower figure; they are accompanied by Carbonate of Copper and Silical Oxyde, with a whitish bloom upon its surface.

I have met with some specimens whose crystals resemble those of the dark green Arseniate, and I have found such specimens to contain a small portion of Arsenic acid; the proper crystal of the Phosphate being; an acute rhomb.