XV. An Account of the Swedish Corundum from Gellivara, in Lapland.
By C. T. SWEDENSTIERNA, or Stockholm,
foreign member of the geological society.
In 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