source
of nearly all the manganese compounds employed in the arts. The most
important use of the mineral is in the iron industry, and the alloys
are employed largely in the production of iron used in casting
car-wheels because of its extreme hardness and toughness. This mineral
is also used in glass factories to neutralize the green color imparted
to glass by impurities in the sand from which it is made. Pyrolusite is
also the principal compound by the aid of which chlorine and oxygen
are produced.
Pyrolusite is mined principally in Virginia, South Carolina and California.
Pyromorphite: Phosphate
of Lead. Lead Phosphate 90%, Lead Chloride 10%. It occurs in crystals,
and in globular, fibrous and granular forms. Color green, yel-
Irw and brown, sometimes orange-yellow, gray or milk-white.
Pyromorphite alone possesses no commercial value, but it is
mined with other compounds of lead as an ore of this metal.
Pyrope: Magnesium
Aluminium Garnet. Color deep red to nearly black. The transparent dark
red stones are used as gems, and are considered very beautiful by many
people. The principal occurrence of the gem variety in this country is
in Utah near the Arizona line, where it is found lying loose in
windblown sand.
Pyrophyllite: Hydrous
Silicate of Aluminium. Occurs nearly always in groups of radiating or
diverging fibers, the bundles of fibers cleaving into flexible sheets
with a pearly luster. When pure this mineral is light shades of yellow,
gray or green. The massive form is used to some extent in making slate
pencils. Dense masses are known as Agalmatolite and is used by the
Chinese as a medium for carving small images.
Pyroxene: A
Metasilicate whose composition varies. Diopside, a green transparent
variety, is sometimes cut for a gem stone; Jeffersonite is a variety
containing zinc; Augite is
the name given to the pyroxene containing alumina.
Pyrrhotite: Magnetic
Pyrite. This mineral occupies the anomalous position of being one of
the important ores of nickel whereas it is essentially a sulphide of
iron. It is brittle and opaque with a metallic luster with color
varying from bronze-yellow to copper-red. It is magnetic and a good
conductor of electricity. This mineral is worked for the sulphur it
contains though its principal use is as a source of nickel which is
used extensively for nickel-plating and in the manufacture of alloys.
