Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/423



XV. An Account of the Swedish Corundum from Gellivara, in Lapland.

By C. T. SWEDENSTIERNA, or ,

.

[Read January, 21st, 1814.]

the spring of 1803, when examining a series of iron ores from Lapland which I had brought with me to Paris, I was greatly surprised to find that the porphyry mortar employed in reducing one of them to fine powder was scratched and lost its polish. Mr. Tennant having nearly at the same time published his discovery on the identity of emery with the sapphire, I was at first induced to believe that the said ore was merely a kind of emery. Upon a further examination however, I found that this ore was as soft as any other from the same place, and was chiefly composed of black and red oxide of iron. These could be separated by the magnet without leaving any earthy residue, which would not have been the case with emery, in which the cutting substance is finely divided and intimately connected with the oxide. I afterwards broke several specimens of the ore, and perceived in some of them very hard crystals the largest of which were of the size of small peas, and exhibited regular faces of an oblique octahedron. I at last succeeded in extracting about half a dozen of them of a perfectly determined form. I then no longer doubted of these crystals being a variety of corundum, which also was ascertained by my teacher in mineralogy, M. Haüy, to whom I presented the purest and most perfect specimens