Carnelian.—A variety of chalcedony, of a clear, deep red, flesh-red, or reddish-white color. It is moderately hard, capable of a good polish, and often used for seals. It is now used but little.
Cat’s-eye.—A variety of quartz or chalcedony exhibiting opalescent reflections from within, like the eye of a cat. The name is given to other gems affording like effects, especially the chrysoberyl.
Chalcedony.—A translucent variety of quartz, having usually a whitish color, and a luster nearly like wax.
Dendrite.—A stone or mineral in which are branching figures, resembling shrubs or trees, produced by a foreign mineral, usually by an oxide of manganese, and the moss agate.
Diamond.—A precious stone or gem excelling in brilliancy, beauty of prismatic colors, and remarkable for extreme hardness. It is found in many hues—green, rose, straw, yellow, etc.—but the straw-colored ones are the most common. The diamond is a native carbon, occurring in isometric crystals, often octahedrons, with rounded edges. It is the hardest substance known. Diamonds are said to be of the first water when very transparent, and of the second and third water as the transparency decreases.
Diopside.—A crystallized variety of pyroxene (a silicate of lime and magnesia), of a clear, grayish-green color; also called mussite.
Emerald.—A precious stone of a rich green color; it is the most valuable variety of beryl. (See [beryl].)
Epidote.—A mineral, commonly of a yellowish-green color, occurring granular, massive, columnar, and in crystals. It is a silicate of alumina, lime, and oxide of iron, or manganese.
Fluorite.—Calcium fluoride, a mineral of many different colors, white, yellow, purple, red, etc., often very beautiful. When crystallized it is commonly in cubes with perfect octahedral cleavage. Some varieties are used for ornamental vessels. Also called fluor spar, or simply fluor. The colored varieties are often called false ruby, false emerald, false topaz, false sapphire, and false amethyst.
Flint.—A massive, somewhat impure variety of quartz, in color usually of a gray to brown or nearly black. (See [quartz].)