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

D1CHE01TE. 107ferent colours blue, when looked at in the direction ofits axis, and dark yellow when regarded at a rightangle.It is found chiefly in hexagonal and dodecahedralprisms. Its cleavage is concave and unequal. Sometimes,the dichroite, when cut, sends out a ray of lightsimilar to that of the asteria.This substance scratches crystal, and is scratched bytopaz its ; specific gravity is 2'88 ;it becomes electricby friction, and acquires polarity by heat. Mixed withborax, it melts into a transparent glass, on which acidshave no power.Its component parts are magnesia, alumina, andsilex, with a little oxide of iron and water.The dichroite is found in primitive rocks, in bluechalk, in pyrites of copper, in the various kinds ofquartz, in felspars, and in scattered flints.It isbrought from Spain, Bavaria, Greenland,Sweden, Norway, and Finland. In Ceylonit is foundin small blue stones. In Connecticut it is embedded ingranite.Blue quartz might be mistaken for dichroite, butquartz is the hardest, and dichroite offers the phenomenonof double colour, which in the former does notexist. Many are similar to the sapphire at first sight,but eventually they are easily to betheir hardness.distinguished by