A Hand-book of Precious Stones

by Meyer D. Rothschild

2. Natrolite. Fusible in fine splinters in the summit of a candle flame without the blow-pipe.

3. Almandite. Does not fuse in candle flame; fuses easily before the blow-pipe in obtuse pieces.

4. Green Actinolite. Fusible before the blow-pipe in coarse splinters.

5. Orthoclase. Fusible before the blow-pipe in fine splinters.

6. Bronzite. Before the blow-pipe becomes rounded only on the sharp edges.

Magnetism.

There are but few precious stones that possess the power to act on the magnetic needle; among them are the chrysolite, cinnamon stone, almandine, pyrope, and garnet.

Transparency.

Precious stones are, on the basis of their relative transparency, divided into four classes, as follows: Transparent, or admitting light freely and clearly; defining objects when used as a lens. Semi-transparent, admitting light, but only partially defining objects. Translucent, admitting light faintly. Opaque, not admitting light.

The more valuable precious stones, excepting opals and turquoises, are generally transparent.