Geology. Lapis-Lazuli.

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,
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London:
David Bogue, Fleet Street,
MDCCCXLIX (1849)The Petersburgh Academy of Sciences has published the following particulars relative to Lapis-lazuli and Mica: "Both these minerals are found in the vicinity of Lake Baikal, especially in the river Hindianka, and in all the rivers which fall from Mount Khamardaban. Mineralogists have not, however, yet succeeded in finding the flow of the lapis-lazuli, notwithstanding the minute researches which have been made in divers points of the localities. Mr. Moor, the mineralogist, who spent two summers on the banks of the Hindianka, succeeded only in discovering the flow of glaucolithe, or calcareous blue spath, and every attempt since made to ascertain the place of the formation of the lapis-lazuli has been unsuccessful. The natives affirm that this precious stone is met with after the heavy rains have washed down the pebbles found in the beds of the rivers. With regard to mica, it is found in great abundance in the neighbourhood of Hindianka, even with the ground, in the form of not very thick flakes, lying upon a bed of soft clay, as if it had been deposited upon it. The inhabitants frequently resort to these places to carry off the mica, which they put into their window-frames in place of glass.