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enstatite. Names have been given to members of this group according to their component minerals, e.g. pyroxenite (augite), diallagite (diallage), hypersthenite (hypersthene), bronzitites (bronzite), websterite (diallage and hypersthene). Closely allied to this group are the hornblendites, consistingessentially of See also:

HORNBLENDE

hornblende. The See also:

TERM

term perknite (Gr. lrepsvbs, dark) has also been used to designate the whole See also:

SERIES (a Latin word from serere, to join)

series. They are essentially of igneous origin, though some pyroxenites are included in the metamorphic complex of the Lewisian of See also:

Scotland; those pyroxene rocks which result from the contact alteration of impure limestones are described as pyroxene hornfelses (calc-silicate hornfelses). The pyroxenites are closely allied to the gabbros and norites, from which they differ by the See also:

ABSENCE (Lat. absentia)

absence of See also:

FELSPAR, or FELDSPAR

felspar, and to the peridotites, which are distinguished from them by containing See also:

OLIVINE

olivine. This connexion is indicated also by their mode of occurrence, for they usually accompany masses of See also:

GABBRO

gabbro and See also:

PERIDOTITE

peridotite and seldom are found by themselves. They are strictly plutonic and often very coarse-grained, containing individual crystals which may be several inches in length. The See also:

PRINCIPAL

principal See also:

ACCESSORY

accessory minerals, in addition to olivine and felspar, are See also:

CHROMITE

chromite and spinels, See also:

garnet, See also:

IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron oxides, See also:

RUTILE

rutile, See also:

SCAPOLITE (Gr. O'Kairos, rod, )tLOoc, stone)

scapolite. They frequently occur in the See also:

FORM (Lat. forma)

form of dikes or segregations in gabbro and peridotite: e.g. in See also:

SHETLAND, or ZETLAND

Shetland, Cortlandt on the See also:

Hudson See also:

RIVER

river, See also:

North Carolina (websterite), See also:

Baltimore, New See also:

ZEALAND (also SEALAND Or SEELAND; Danish Sjaelland)

Zealand, and in See also:

Saxony. The component minerals often have a See also:

close resemblance to those of the surrounding rock. By decomposition the rocks consisting of pyroxene pass into serpentines, which sometimes preserve the See also:

ORIGINAL

original structures of the See also:

PRIMARY

primary minerals, such as the lamination of hypersthene and the rectangular cleavage of augite.

Under pressure-See also:

METAMORPHISM (Gr. ise-rci, change of, and liop¢i, shape)

metamorphism hornblende is See also:

DEVELOPED

developed and various types of See also:

AMPHIBOLITE

amphibolite and hornblende-schist are produced. Occasionally rocks See also:

rich in pyroxene are found as basic facies of See also:

NEPHELINE

nepheline See also:

SYENITE

syenite; a See also:

GOOD, JOHN MASON (1764-1827)

good example is provided by the melanite pyroxenites associated with See also:

BOROLANITE

borolanite (q.v.) at Ledbeg in See also:

SUTHERLANDSHIRE

Sutherlandshire. (J. S.

End of Article: PYROXENITE

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PYRRHO OF ELIS (c. 360—270 B.C.)