CROCIDOLITE, or TIGER-EYE
Is a variety of hornblende found in gem form in South Africa; otherwise in the United States.
It
consists of thin, silky fibres compacted together, and is probably
converted from some original fibrous stone to a variety of quartz, but
retaining the fibrous form.
Hardness, 4 to 7; specific gravity, 3 to 3.3.
Lustre silky; chatoyant.
When cut en cabochon it exhibits more or less chatoyancy similar to the cat's-eye.
The composition is very varied, and consists of silica, oxide of iron, soda, magnesia, and water in varying proportions.
Colors, light brown, brownish yellow, dark green, and greenish blue. The blue variety is sometimes called " hawk's-eye."
It is usually cut for cameos,
paper-weights, umbrella-handles, etc. Since the discovery of large
quantities at the Orange River, Griqualand-West, in South Africa, it is
not much used for jewelry.
Tiger-eye
is frequently sold as petrified wood, and is artificially colored to
imitate some of the finest shades of Oriental cat's-eve.
