It occurs in small quantity in association with iron in meteoric stones;
with this exception it is not found native. The metal may be obtained by
the reduction of its sesquioxide by carbon at an extreme heat.

Manganese forms no less than six different oxides--viz., protoxide,
sesquioxide the red oxide, the binoxide or peroxide, manganic acid, and
permanganic acid. The protoxide occurs as olive-green powder, and is
obtained by igniting carbonate of manganese in a current of hydrogen.
Its salts are colorless, or of a pale rose color, and have a strong
tendency to form double salts with the salts of ammonia. The carbonate
forms the mineral known as manganese spar. The sulphate is obtained by
heating the peroxide with sulphuric acid till there is faint ignition,
dissolving the residue in water and crystallizing. It is employed
largely in calico printing. The silicate occurs in various minerals.

The sesquioxide is found crystallized in an anhydrous form in braunite,
and hydrated in manganite. It is obtained artificially as a black powder
by exposing the peroxide to a prolonged heat. When ignited it loses
oxygen, and is converted into red oxide. Its salts are isomorphous with
those of alumina and sesquioxide of iron. It imparts a violet color to
glass, and gives the amethyst its characteristic tint. Its sulphate is a
powerful oxidizing agent.

The red oxide corresponds to the black oxide of iron. It occurs native
in hausmannite, and may be obtained artificially by igniting the
sesquioxide or peroxide in the open air. It is a compound of the two
preceding oxides.

The binoxide, or peroxide, is the black manganese of commerce, and the