Sulphuret of Copper; Swimming Pyrites Enlarge
Feb 1 1809. Publish’d by Jas Sowerby London
British Mineralogy
CCCI
Cuprum sulphureum

Sulphuret of Copper; Swimming Pyrites

  • Div. 2. Imitative.

It is now no novelty to find Metals of very light specific gravity, since Mr. Davy’s discovery of Sodium and Potassium, yet we have no account of Swimming Copper Pyrites, that I know of, I am therefore glad to treat the world with this novelty. Some lime ago Mr. Carne favoured me with the Swimming Quartz which had some porous Sulphuret and Oxide of Copper about it, which gave me reason to suppose some Swimming Copper Ore might be found, since which time he has kindly informed me that he has procured a specimen, and I have, by chance, received this from the same place*.

It would seem from its appearance to have been formed by passing among the irregular interstices of some shattered part of a rock which is completely gone in the same manner as from the Quartz above. It is in somewhat plated chambers irregularly angular of various dimensions. It is extremely friable, and the tenuity of the plates or divisions will scarcely allow of its being handled, h is a kind of exception to the rule by which we judge of the specific gravity or weight of Metals by the hand, to distinguish them from the Combustibles and Earths, and is a good example of an argument regarding the gravitating principle, that, under certain circumstances, the Metals may lie above the Earths and Combustibles, when in a divided state. Thus it is lighter than water in this porous form, although its solid specific gravity in comparison to that of Water is as 4315 to 1000: so that, in judging of specific gravity, the solid state of the substance must be attended to.

  • * From Trelistian Mine, near Penzance in Cornwall.
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