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AMPHIBOLE

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Originally appearing in Volume V01, Page 883 of the 1911 Encyclopedia Britannica.

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AMPHIBOLE , an important See also:

GROUP

group of See also:

rock-forming minerals, very similar in chemical See also:

composition and See also:

general characters to the pyroxenes, and like them falling into three See also:

SERIES (a Latin word from serere, to join)

series according to the See also:

SYSTEM

system of See also:

CRYSTALLIZATION

crystallization. They differ from the pyroxenes, however, in having an See also:

ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle between the prismatic cleavage of 56° instead of 87°; they are specifically lighter than the corresponding pyroxenes; and, in their See also:

OPTICAL

optical characters, they are distinguished by their stronger pleochroism and by the wider angle of extinction on the See also:

PLANE

plane of symmetry. They are minerals of either See also:

ORIGINAL

original or secondary origin; in the former See also:

case occurring as constituents (See also:

HORNBLENDE

hornblende) of igneous rocks, such as See also:

GRANITE (adapted from the Ital. granite, grained; Lat. granum, grain)

granite, See also:

DIORITE (from the Gr. S&oi4eiv to distinguish, from hA through, Epos, a boundary)

diorite, See also:

ANDESITE

andesite, &c. Those of secondary origin have either been See also:

DEVELOPED

developed (See also:

TREMOLITE

tremolite) in limestones by contact-See also:

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

metamorphism, or have resulted (actinolite) by the alteration of See also:

AUGITE

augite by See also:

DYNAMO (a shortened form of " dynamo-electric machine," from Gr. Sbvaµis, power)

dynamo-metamorphism. Pseudomorphs of amphibole after See also:

PYROXENE

pyroxene are known as uralite. The name amphibole (from the Gr. aw/,i3oXos, ambiguous) was used by R. J. See also:

HAUY, RENE JUST (1743-1822)

Hauy to include tremolite, actinolite and hornblende; this See also:

TERM

term has since been applied to the whole group. Numerous sub-See also:

SPECIES

species and varieties are distinguished, the more important of which are tabulated below in three series. The formulae of each will be seen to conform to the general See also:

META

meta-silicate See also:

formula R"SiO3.

End of Article: AMPHIBOLE

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