Under
the influence of radium rays it becomes green. This semiprecious stone
is extremely popular as a gem. Its color, light lilac-red, has been
compared to pink Topaz, Rubellite and light-colored Amethyst. Its
unique color values, however, distinguish it from any of these stones.
Labradorite: Labrador
Spar, a beautiful variety of opalescent feldspar, the finest specimens
of which come from Labrador. It occurs in very thin tabular crystals,
also massive or granular, and sometimes cryptocrystalline or
hornstone-like. Color gray, brownish, greenish; sometimes colorless and
glassy and also bluish-green. There is usually a beautiful change of
colors in the cleavable varieties, blue and green being the
predominating colors, but yellow, fire-red and pearly-gray also appear.
It occurs abundantly through the central Adirondack region in northern
New York.
Labradorite was first brought from the coast of Labrador by a Moravian missionary in 1770, and was called Labrador-Stone. It is used as a semi-precious or ornamental stone.
Lapis Lazuli: An
Aluminous mineral of a rich blue color and was formerly much used as a
gem stone. Good gem material is brought from Siberia and Chile,
although it is still produced in the historic localities in Persia.
Compared with other semi-precious stones, Lapis Lazuli has small value.
It is used in jewelry, for small ornaments such as bowls and vases, in
the manufacture of mosaics, and as a pigment, when ground, under the
name of ultramarine. (See Lazurite.)
Laumonite: Silica
51%, Alumina 22%, Lime 12%. This mineral occurs in monoclinic crystals
and in radiating fibrous aggregates. Color white, grayish, reddish or
yellowish. Transparent to translucent. It occurs in cavities of basic
volcanic rocks, and in veins in clay, in Scotland, Nova Scotia,
Colorado, Lake Superior region, and New Jersey.
Lauriumite: A prismatic hydroxychlorid of Lead, found in lead slags in the vicinity of Laurium, Greece.
Lazulite: Hydrous
Aluminium-iron Magnesium Phosphate. A mineral of a light blue, or
azure-blue color, occurring in small masses or in oblique four-sided
prisms. It occurs
in Switzerland and Brazil; abundant in corundum mines in North
Carolina, and in fine blue crystals in Georgia. The name is derived
from the Arabic word azul, meaning heaven.
Lazurite: (see Lapis Lazuli).
