HIDDENITE
Or lithia
emerald, was named after Mr. Hidden. It is found only in North
Carolina. It is said to have been first discovered in 1879, by Mr.
Hidden, though J. A. D. Stevenson, of Statesville, North Carolina, had
specimens at that time in his cabinet which he claimed to have had for
some years.
It is a variety of spodumene or triphane.
Crystallization
monoclinic. When in rock, it is found as unchanged crystals. The ends
of the crystal generally vary in color, yellow and green.
Hardness, 6.5 on the prism faces; across them, nearly that of the emerald; specific gravity, 3.17 to 3.19.
Lustre vitreous; transparent.
Very perfect prismatic cleavage; fracture uneven.
Double refraction (index, 1.67); dichroic; electric in polished state.
Composition: silica 64.34; alumina, 27.61; lithia, 8.05, with traces of iron and soda.
Melts to clear glass under the blow-pipe, and is attacked by salts of phosphorus.
Color, light yellow to yellowish green and deep yellow; rarely colorless.
It is cut step and brilliant.
Spodumene
Is
sometimes cut as a gem. It is found in greenish white, grayish green,
yellow, and very light red, as pitted and altered fragments. It is
difficult to cut on account of its very easy cleavage, and because it
is harder in one direction than the other. A few of amethystine color
have been found in the United States, but the transparent variety is
almost confined to Brazil.
