Putting on one side minor and accidental ingredients, although to these the colours, absorption-bands, opalescence, etc., of the stone are due, the percentage composition of zircon approaches.—
Zirconia | 67 | Silica | 33 |
Spodumene.
Until lately spodumene was not recognised as a stone which could be cut and polished as a gem; but a large importation from Brazil of brilliant and transparent crystals of yellow spodumene led to some specimens being cut and polished. The easy cleavage of the stone renders its working and mounting difficult matters. Spodumene crystallizes in the monoclinic system, and resembles in appearance the chrysoberyl. Its hardness is 7, and its specific gravity 3·2. It contains in 100 parts:
Silica | 64·2 | Iron oxide | ·4 |
Alumina | 29·0 | Lithia | 6·0 |
with traces of soda, lime, potash, and water.
Hiddenite.
This beautiful green stone is transparent and of a brilliant green hue, not unlike that of a rather yellowish green emerald. It is a variety of spodumene, a mineral generally of a dull well-nigh opaque greyish or creamy colour, but sometimes of a brilliant straw yellow and transparent. Hiddenite rarely occurs in crystals sufficiently large for cutting into gem-stones. A cut stone, however, nearly perfect, weighed 21/2 carats, and was sold for more than $125 a carat. It has been found as yet in but one locality, Alexander county, North Carolina. It was discovered by Mr. W. E. Hidden. Its hardness is 63/4, and its specific gravity 3·17.
Kunzite.
This newly-discovered variety of spodumene is remarkable for the very large size of the crystals in which it occurs, for the