s CuSiO3 + 2H2O. The hardness
(2-4) and specific gravity (2.0-2.8) are also variable. It has recently
been suggested that the material may really be a mixture of more than
one hydrous copper silicate, since differences in the microcrystalline
structure of the different concentric layers of which the masses are
built up may be detected. Various impurities (silica, &c.) are also
commonly present, and several varieties have been distinguished by
special names: thus dillenburgite, from Dillenburg in Nassau, contains
copper carbonate; demidoffite and cyanochalcite contain copper
phosphate; and pilarite contains alumina (perhaps as allophane). The
mineral occurs in the upper parts of veins of copper ores, and has
resulted from their alteration by the action of waters containing silica
in solution. Pseudomorphs of chrysocolla after various copper minerals
(e.g. cuprite) are not uncommon. It is found in most copper mines.

The name chrysocolla (from [Greek: chrysos], gold, and [Greek: kolla],
glue) was applied by Theophrastus and other ancient writers to materials
used in soldering gold, one of which, from the island of Cyprus, may
have been identical with the mineral now known by this name. Borax,
which is used for this purpose, has also been called chrysocolla.

A mineral known as pitchy copper-ore (Ger. _Kupferpecherz_), and of some
importance as an ore of copper, is usually classed as a variety of
chrysocolla containing much admixed limonite. It is dark brown to black
in colour, with a dull to glassy or resinous lustre, and resembles pitch
in appearance. In thin sections it is translucent and optically
isotropic, and recent examinations seem to prove that it is a
homogeneous mineral and not a mechanical mixture of chrysocolla and
limonite. (L. J. S.)

CHRYSOLITE, a transparent variety of olivine, used as a gem-stone and
often called peridot. The name chrysolite, meaning "golden stone"
([Greek: chrysos] and [Greek: lithos]), has been applied to various
yellowish gems, notably to topaz, to some kinds of beryl and to
chrysoberyl. The true chrysolite of the modern mineralogist is a
magnesium silicate, referable to the species olivine. It is appropriate
to call the lighter coloured stones inclining to yellow chrysolite, and
the darker green stones peridot. Certain kinds of topaz, from the
Schneckenstein in Saxony, are known as Saxon chrysolite; while
moldavite, a substance much like a green obsidian, is sometimes call