|
CHAPTER XVII.
|
||
|
|
||
|
LABRADORITE AND OTHER GEMS.
The opinion has been advanced that labradorite was
unknown until about a century ago, when it was discovered at Labrador, from which it received its name, but this statement can apply only to the inhabitants of the Eastern Continent, since Indian ornaments made of this stone were found by the Spaniards during their invasion of America. It occurs in volcanic matter, and forms a constituent of porphyry, verde antique, and some other rocks. This mineral is complex in its chemical nature, comprising a variety of substances — silica, alumina, lime, soda, iron, and sometimes magnesia, potash, and water, and, notwithstanding its comparative softness, admits a fine polish, which constitutes it a beautiful and desirable decorative stone. It is employed to some extent for jewelry. Labradorite is of a grayish color, but, when seen in certain
directions, it displays chatoyant reflections, usually of blue, green, violet, and gold, " equal to those which ornament the most beautiful butterfly." There is a difference in this respect among the numerous specimens of this mineral to be met with ; in some instances, red, gray, amber, and orange tints are conspicuous, while in others the play of colors is wanting. This iridescent quality is due to its peculiar structure, which, like the opal, encloses fissures, occupied, it is conjectured, from experiments with the magnet, by thin films of iron, and per- 325
|
||
|
|
||