15.—Calamine.
Occurs
in crystals and masses ; glossy lustre; harder than marble; brittle;
heated it swells up, becomes and emits a green light; dissolves, when
powdered, in hot sulphuric acid without effervescence; gravity 3.4.
Value.—An ore of zinc yielding from forty to sixty per cent.
Localities.—Found in limestone rock with other ores.
16—Cannel Coal.
Occurs
in compact masses ; dull lustre; brittle, breaking with a curved
surface ; burns readily but does not melt; does not soil the fingers;
gravity about I-2. Value.—Used for fuel and for making gas, oil and ornaments. 17—Carnelian.
Occurs
in masses or pebbles; at first grayish, but by exposure to the sun
becomes uniform Hesh, red or brown, never striped,—although Varnelian may form one of the bauds of an Agate; brittle, breaking with a curved surface; very hard; takes a fine polish; glassy or resinous lustre; gravity 2'6.
Value.—Used for jewelry. When of two layers, white and red, (properly called sardonyx), it is used ior cameos.
Localities.—Same as Agate.
18.—Celestine.
Occurs
crystallized, fibrous and massive; color white, often faint bluish;
glassy lustre ; very brittle; under the blow-pipe crackles and melts,
tinging the rlarne red; does not dissolve in acids; gravity 4.
Value.—The source of nitrate of strontia, used in fire-works.
Localities.—Found in limestone, gypsum and sandstone.
19.—Creussite.
Occurs
in crystals, in powder or masses; glassy lustre; brittle; dissolves in
nitric acid with effervescence; heated strongly on charcoal, crackles
and fuses, giving a' globule of lead ; gravity 6-4.
Value.—A rich ore of lead yielding seventy-five per cent.
Localities.—Found in lead mines.
20.—Chromic Iron.
Occurs
in compact masses; powder dark brown; small pieces sometimes attracted
by the magnet; brittle, breaking with uneven surface; with borax melts
into a green globule; not acted upon by acids; little lustre; gravity
4'4.
Value.—Used in making the chrome pigments.
Localities.—Found in terpentine.
21.—Cinnabar.
Occurs
in granular or earthy masses j resembles iron-rust, but is a
yellowish-red ; powder scarlet; easily cut with a knife; thrown on
red-hot iron, evaporates, giving off odor of sulphur; rubbed on copper,
"silvers" it; gravity 9, or about as heavy as Copper.
Value.—The source of mercury (containing eighty-four per cent.) and vermillion.
Localities.—Found in slate and limestone rocks.
22.—Cobalt Pyrites.
Occurs
crystallized and massive; does not scratch glass easily; metallic
lustre; tarnish, copper-red; powder, blackish-gray; brittle; heated on
charcoal gives oft sulphur fumes; heated with borax gives a blue glass;
gravity 5.
Value.—An ore of cobalt, -yielding twenty per cent.
Localities,—Usually found in slate or granite rocks with Copper Pyrites.
