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

116 GEMS.Zirconium .. .. 64*5Silex 32Iron 2Lead .. .. .. 1'5Its specific gravity, greater than thatof Ceylon, is from 4-38.lightof the jacinthIn spite of its brightness, itsis more resinous than the other. Under theaction of the blow-pipeit does not melt, but losescolour and becomes white.Jacinths have very often a defectwhich diminishestheir beauty and value, viz., bubbles in the interior, ofwhich no satisfactory explanation can be given.Some of an inferior quality, yellowish white, arefound in Bohemia, Silesia, and Spain.The essonite and idocrasio were also called jacinth,but we cannot see the reason, as they do not in anyrespect resemble that stone.The gem named by the ancients hyacinthus is acorundum, and not our jacinth ;we mayrather believethat the latter was by them called lyncurium.They frequently used the lyncurium, pale and darkcolour equalty, for engravings and camei ;but for thiswork they preferred the dark kind, which, perhaps,was that which was called mono, on account of itsmulberry colour, and of which Pliny says: ad ectypassculpturas faciendas.