LABRADORITE, See FELDSPAR LAPIS LAZULI
Rock-like gem material in which the blue color is imparted principally by lazurite; also contains calcite as white streaks or spots and pyrite crystals; the finest grade is very fine-grained, uniform in color, lacks calcite, and if it con¬tains pyrite, the latter is in evenly distributed pinpoint crystals; best material from Afghanistan; good mottled material from Lake Baikal region; fair from Chile and abundant; fair to good from California and Colorado but supplies meager. The most compact material can be faceted to a fine finish but most lapis is employed in cabochons, and in small to large carvings.
LAUREUTE, see IDOCRASE LAZULITE
A dark to medium blue mineral resembling lazurite but rare and seldom found in masses large enough to provide cabochons; very rarely, small clear crystals are found in some diamond-bearing gravels of Brazil.
LAZURITE, see LAPIS LAZULI LEPIDOLITE
Soft pink to mauve massive lithium mica rock occurring in pegmatites; has
been used for spheres, bookends, and other ornamental objects; eventually fades.
California, Maine, etc.    lb.    1.00-1.25
LEUCITE
Faceting material from ]/$”-l/i” crystals occurring in lavas;  very pale straw color; collectors’ gem only.
LIBYAN DESERT GLASS, See TEKTITE LINTONITE, see THOMSONITE LLANITE, LLANOITE
Granite rock containing small blue chatoyant quartz grains in brownish groundmass; soft; useful for ornamental objects only.