The color of the carbon, or carbonado, as it is called by the Brazilians, is generally black, but it may be light-brown or of a greenish gray color, when diluted with clay. It is always opaque, but is not always compact, being sometimes quite porous, like pumice-stone. It never crystallizes, but generally appears in angular pieces in lumps or concretionary masses whose specific gravity is 3 to 3.4, while that of the transparent diamond is 3.5. The black and perfectly crystallized diamond, which is very rare, is not to be confounded with this variety. The hardness of the carbon is equal to that of the transparent diamond, and probably some of the purest and most compact specimens are harder even than the limpid variety; for the black gems are generally harder than the light-colored, and we have for instances the deep-blue sapphire, the black tourmaline, etc. At first this newly discovered mineral was pulverized, and its powdered dust used to polish diamonds and other gems, and was then sold for a few francs the karat. Lately, however, science has applied its use to new inventions; and the demand for it in its application to the drill and the saw has increased its value to several dollars the karat, and the price is still increasing. Its advantages over the crystallized varieties are very decided, and it is as hard and has no cleavage planes, and is therefore far better able to resist the effects of shock. The only diamond known to have been found in modern times in Western Europe is that picked up in a brook in the County of Fermanagh in Ireland. Its weight was not given, but it was stated to be of a reddish cast and valued by Mr. Rundell at twenty guineas. Some mineralogists have maintained that the stone in question was not in place and was probably brought in the crop of some bird of passage from Brazil or the tropical countries of America. To us, however, a more plausible and probable theory would be that the stone was in place, and that its presence is no more remarkable than the gold nuggets found in the same country. In fact, this instance is no more strange than the finding of the great American diamond in Virginia, which was also a solitaire and many miles below the auriferous fields whence it is supposed to have drifted. We shall not be surprised to learn of the occurrence of diamonds in other parts of Europe. Pliny ends his chapter on the diamond by stating on the authority of Scepsius that diamonds are found in Germany and in the island of Basilia along with amber.