TIGEREYE
Narrow seams of an asbestos mineral replaced by quartz; the original fibrous structure is retained, resulting in chatoyancy in polished specimens; yellow, brownish-yellow, brown, red, blue, green, and streaked in these colors; yellow is by far the most abundant kind; supplied exclusively from South West Africa. Brown and yellow kinds turn red upon heat-treatment; they […]

SMOKY   QUARTZ
Includes all varieties with hues from pale brownish smoky to rich brown to nearly black; cairngorm is rich brown material and morion is material of very dark color; can be heat-treated to lighten or drive off color completely; smoky quartz with yellowish tinge is commonly a mixture of smoky and citrine and can be […]

ROCK   CRYSTAL
Colorless quartz; very abundant in facet-grade crystals to several pounds weight; large flawless pieces capable of cutting spheres in excess of 3″ are rare and cost rises sharply as size increases above this; electronic-grade crystals of 5-10 lbs. may realize as much as f50.00 per pound; much of facet material is left over from […]

PRASE
This varietal name was once applied to fine-grained quartzite colored dark green by inclusions of amphibole; some authorities believe it should also apply to green jaspers; the term is now rarely used and material using this name is very seldom sold.

QUARTZ
The numerous varieties of this mineral provide more inexpensive gem material than all other species combined. Crystalline varieties are those with individual crystals large enough to see with the naked eye or under weak magnification; cryptocrystalline varieties require high magnification and typically […]

PENTLANDITE
Sometimes cut into cabochons for collectors; brilliant metallic luster.
Ontario lb. 1.00-3.00
PERIDOT, see OLIVINE PERISTERITE, See FELDSPAR PERTHITE, See FELDSPAR PETALITE
Rare pegmatite mineral; colorless to pink; sometimes facetable from clear
areas in colorless crystals from New South Wales; fairly hard, brittle; inclusions
common; collectors’ […]

OBSIDIAN
A common glass-like volcanic rock used extensively for tumbled gems, small carvings, ornamental objects, and jewelry; brittle and weak; black most com¬mon but also brown, reddish-brown, and streaked material, the so-called “flow” obsidians; Apache tears are black to dark brown clear nodules weathered from perlite rock; sheen obsidians contain numerous minute spangly inclusions, the best […]

NEPHRITE
Fibrous actinolite or tremolite; hard and extremely tough, the classical jade predating jadeite jade and much revered by the ancient Chinese; translucent to nearly opaque; many hues, but seldom as vivid as jadeite, include near-white, tan, yellow, brown, brownish-red, yellow-green, olive-green, dark green to nearly black, etc. Formerly from Khotan, the ancient Chinese source, and […]

MAGNESITE
Rarely in clear facetable crystals from Brazil providing gems to 15 ct. for collectors.
Brazil, colorless, to 50 gm.+ gm. .75-1.50
MAGNETITE
Black magnetic iron ore sometimes cut as a curiosity.
MALACHITE
Bright green copper carbonate known from antiquity and extensively used for ornamental items and carvings, and for beads and other forms of […]

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 […]