bright
green. Translucent to opaque. Malachite is a secondary mineral formed
as an oxidization product of other copper ores by the action of
percolating waters charged by carbon dioxide.
In
addition to its use as an ore of copper, the radial and massive forms
are employed as ornamental stones for interior decoration. It is especially
prized in Russia for this purpose, the large interior columns of St.
Isaac's Cathedral in Petrograd, being made of Malachite. The attractive
banded effect is well brought out on a polished surface, and it is used
for clock cases, table tops, paper-weights, vases, etc. In recent years
it has been used extensively for popular priced jewelry.
Manganite:
Hydrous Manganese Oxide. Oxygen 27%, Manganese 62.4% Usually occurs in
groups of black columnar or prismatic crystals, and in stalactites; is
black in color with a reddish-brown streak. Through loss of water,
Manganite passes readily into Pyrolusite. It is a non-conductor of
electricity.
Marble: Any
species of calcareous stone or mineral, of a compact texture, beautiful
in appearance and susceptible to a good polish. Its principal use is as
a building stone, and has been used for this purpose since the earliest
times.
Egyptian
Marble is black calcite, handsomely veined with yellow Dolomite;
"Death's Robe" of Italy, is black calcite with white fossil shells
enclosed; "Marble of Languedoc" is fine deep red with a little white or
gray from St. Beaume, France; Bird's Eye Marble is gray with white
crystalline points and is from Central New York; Shell Marble consists
largely of fossil shells; Ruin Marble is yellow to brown, showing
figures like fortifications and temples in ruins, from Florence, Italy;
Breccia Marble is made of fragments of limestone cemented together and
is often very beautiful when the fragments are of different colors;
"Puddingstone" marble consists of pebbles or rounded stones cemented
together; Serpentine marble is cut and polished slabs of serpentine
rock.
Marcasite: Iron
Disulphide. Sulphur 53%, Iron 47%. This mineral resembles Pyrite so
closely that in massive specimens it is difficult to distinguish
between the two.
They are nearly alike in color, hardness and in chemical properties.
The cockscomb variety is found in Derbyshire, Eng., and as crystals
in Hungary. In the United States it is especially abundant in the
Mississippi valley.
Margarite: Calcium
Mica. This mineral usually occurs in tabular plates but also as scaly
aggregates. Its color is white, yellowish, grayish or reddish, and it
is transparent or translucent. It occurs in the Tyrol, Switzerland; in
the emery
