Mechanical an Useful arts. A New Mineral Useful in Arts.

The Year-Book of Facts in Science and Art
Exhibiting the Most Important discoveries and Improvements of the past year,
in mechanics and the useful arts; natural philosophy; electricity; chemistry; zoology and biology; geology and geography; meteorology and astronomy.
By John Timbs,
editor of "the Arcana of Science and Art."
London:
David Bogue, Fleet Street,
MDCCCXLIX (1849)We learn that Mr. Blake, of Akron, Ohio (U.S.), has discovered a mineral, in the neighbourhood of the latter place, which promises to be of great value. He has visited Washington, and obtained a patent for it. When first dug up, it is of the consistence of tallow, and gradually hardens in a few days, so as to resemble slate, and finally it becomes as hard as rock. It is of the colour of indigo. It is impervious both to water and fire, and admits of the finest polish. When reduced to powder, and mixed up with linseed-oil, it has the appearance of black paint, and may be spread over wood, canvas, &c. Roofs have been guarded by it against fire; and as it does not absorb the rain, it protects the rafters from decay. It consists of about one-half of silica, one fourth alumina, with less proportions of magnesia, black oxide of iron, sulphate of iron, lime, and carbon.

— Sheffield Iris.