Stibnite:
Antimony Tri-Sulphide. Sulphur 28.6%, Antimony 71.4%. This is the
commonest and most important ore of Antimony and occurs in prismatic
and acicular crystals, in radiating groups of crystals, and in fibrous
masses. Some of the crystals are very complicated and have many
terminal planes. A crystal from Japan was found to possess a
termination of 84 planes. This mineral fuses easily, thin splinters
being melted in the flame of a candle.
The
finest crystals, some of them 20 inches in length, come from mines on
the Island of Shikoku, Japan. They also occur in Nova Scotia, at many
points in Eastern United States, and many mining districts in the Rocky
Mountains.
This
mineral was employed by the ancients for coloring the hair and eyebrows
and to increase the apparent size of the eye. At present it is used in
vulcanizing rubber, in the manufacture of safety matches, percussion
caps, certain kinds of fireworks, etc.
Its
principal value is as an ore of antimony, for practically all of the
antimony used in the arts, is from Stibnite. Antimony is chiefly
valuable as an alloy with other metals, (see Antimony).
Stilbite:
Hydrous Silica of Calcium and Aluminium. Silica 57%, Alumina 17%, Lime
8%. This mineral occurs in twinned crystals, in sheaf-like aggregates,
in radiating bundles, and in thin platy prisms, colorless or white,
grayish, greenish, yellowish, red or brown. Transparent or translucent,
with a glassy luster that is almost pearly. This mineral belongs to the
Zeolite group and occurs in Scotland, Ireland, India, and Sweden; is
abundant in old volcanic rocks in Nova Scotia; and appears also in
Connecticut, Colorado and at Bergen Hill, N. J.
Stilpnomelane:
Hydrous Silicate of Iron, Aluminium and Magnesium. This is a
greenish-black mineral with a luster that is partly pearly and
sometimes sub-metallic, or brass-like. It occurs in Sweden with
Actinolite, in veins sometimes four inches thick.
Stilpnosiderite: (Limonite)
Stolzite:
Lead Tungstate. Tungsten Trioxide 51 %, Lead Oxide 49%. Occurs in
green, yellowish-gray, brown and red tetragonal crystals. Its principal
localities are the tin-mines in Bohemia; copper veins in Chile; and at
Southampton, Mass., associated with lead compounds.
Stromeyerite:
Sulphide of Silver and Copper. Silver 53%, Copper 31 %, Sulphide 16%.
It is usually massive, but occurs also in simple and twinned crystals,
dark
steel-gray in color and streak It occurs associated with other sul-
