Satin Spar: A
fine fibrous, silky variety of either Carbonate or Sulphate of Lime. A
fine fibrous variety of Calcite; a silky fibrous variety of Aragonite;
and a finely fibrous
variety of Gypsum.
Scapolite: One
of a group of tetragonal silicates containing Aluminium, Calcium and
Sodium, white, or grayish-white in color except when impure, when it is
much darker. Occurs in Prussia, Italy and Norway; also in New York,
Connecticut and Massachusetts.
Scheelite: Calcium
Tungstate. Tungsten 80%, Lime 20%. It sometimes contains a little
molybdenum in place of some of the tungsten. It occurs in crystals,
also in reniform
and granular masses; is white, yellow, brown, greenish or reddish in
color.
This
mineral is valued commercially as a source of Tungsten, which is used
in the manufacture of tool-steel, electric furnaces and targets for
Roentgen Rays. It is employed also as filaments in electric light
bulbs and other minor purposes.
It
is found in Bohemia, Saxony, Cumberland, England; also in Connecticut,
Colorado, Arizona, Nevada, and other places in the United States.
Scolecite: Silica
50%, Alumina 26%, Lime 14%. This mineral occurs in silky fibrous and
dense radiating masses, and also in slender crystals, transparent or
translucent, in cavities of volcanic rocks and in veins. Crystals have
been found on Roman tiles that have been exposed for centuries to the
waters of the hot springs at Plombieres, France. It occurs also in
Switzerland, Iceland, Scotland and at Table Mountain, Colorado.
Selenite: A
transparent crystallized variety of Gypsum, occurring either in
distinct crystals or in broad folia, the folia sometimes a yard across
and transparent throughout. It is usually flexible, yielding a fibrous
fracture. Handsome Selenite occurs near Lockport, New York, (see
Gypsum).
Sepiolite: Hydriated Silicate of Magnesium, (see Meerschaum).
Serpentine: A Magnesium Silicate. Silica 44%, Magnesia 43%.
Sometimes a part of the magnesia is replaced by iron,
giving rise to the many colors of the numerous varieties.
It occurs in crystals, fibrous, foliated and massive, with color greenish,
brownish, white or gray. The variety known as "noble serpentine" is
