Proustite: A
Sulphide of Arsenic and Silver. Silver 65%. It is sometimes called
"Light Ruby Silver" on account of its color. It is ruby-red by
transmitted light and grayish-black by reflected light. Handsome
crystals occur in Saxony and in Chile. In the United States it is quite
abundant in the Ruby District, Colorado. It is mined as an ore of
Silver. (See Pyrargyrite.)
Psilomelane: An
ore of Manganese occurring in smooth botryoid forms, and also in
masses. Color iron-black to steel-gray. It occurs in Vermont, Michigan,
Tennessee,
Arkansas and California. At many of these points it is mined as an
ore of manganese.
Puddingstone: A
variety of marble consisting of pebbles or rounded stones cemented
together by different substances. Pieces cut crosswise and polished are
very ornamental.
Pyrargyrite: "Dark
Ruby Silver." Silver 60%, Antimony 22%, Sulphur 18%. This important ore
of Silver occurs in crystals very rich in form, not less than 150
having been reported. Its color is deep red in transmitted light and
grayish-black in reflected light. The crystallized varieties occur in
Saxony, Bohemia, Hungary and Chile. The massive varieties are mined as
an ore of Silver at Guanajuato, Mexico and in several of the Western
States.
Pyrite: Iron
Disulphide. Sulphur 53%, Iron 47%. This is one of the most common of
minerals and is found under a great variety of conditions as crystals,
as crystalline aggregates, and crystalline masses. Its bright yellow
color led the early miners to call it "Fool's Gold." With steel it
strikes fire, hence its name from the Greek word meaning fire. It is a
good conductor of electricity and is strongly thermo-electric.
Pyrite
is mined in many localities in the United States, Virginia being by far
the largest producer. A beautiful iridescent Pyrite is abundant in
Frizington, Cumberland, England.
Pyrite
is used principally in the manufacture of Sulphuric Acid which enters
into many manufacturing processes. The greater portion of it is
consumed in the artificial fertilizer industry, in making ink and disinfectants.
Pyrolusite: Dioxide
of Manganese. This mineral occurs in columnar and granular masses. It
is soft, often soiling the fingers, with color iron-brack to steel-gray
or bluish.
Together with other manganese ores with which it is mixed, it is die
