Gems Notes and Extracts Augusto Castellani, Mrs. John Brogden 1871

LAPIS LAZULI, OR LAZULITE. 135I believe that this difference isdifferent compositionmore the result of aof the stone than of the error ofchemists, as in experiments I have "been able to observethat all lapis lazuli do not present the same characteristics.Thus, those that come from Persia andChina unite to a finer colour an equal and very finetexture, almost similar to that of the agate ;and itshardness is greater than of that found in the Siberiansteppes, which to a darker colour unites a granulatedtexture, and is of a much inferior quality. WhenceI believe that some comparative experiments wouldhelp to explain the cause of so much diversity, andrender it possible to divide the lapis lazuli, like othergems, into Oriental and Western.This gem, when exposed to a strong heat, melts intoa yellowish-black mass.Under the action of the blowpipeit forms a white crystal, but, when mixed withborax, it melts with effervescence into a very clearcrystal.As I have remarked, the most beautifulcome from