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PYRARGYRITE

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Originally appearing in Volume V22, Page 686 of the 1911 Encyclopedia Britannica.

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PYRARGYRITE , a See also:

MINERAL

mineral consisting.of See also:

SILVER

silver sulphantimonite, Ag3SbS3, known also as dark red silver ore, an important source of the See also:

metal. It is closely allied to, and isomorphous with, the corresponding sulpharsenite known as See also:

PROUSTITE

proustite (q.v.) or See also:

LIGHT

light red silver ore. " See also:

RUBY (Lat. rubeus, red)

Ruby silver " or red silver ore (See also:

German Rotgiiltigerz) was mentioned by G. See also:

Agricola in 1546, but the two See also:

SPECIES

species so closely resemble one another that they were not completely distinguished until chemical analyses of both were made by J. L. See also:

Proust in 1804. From Vyse. 0 S 10 ISM / See also:

PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

Place. See also:

King. Date B.C. See also:

BASE

Base. See also:

ERROR (Lat. error, from errare, to wander, to err)

Error.

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. Height. See also:

AZIMUTH (from the Arabic)

Azimuth. Medum . . . Sneferu 4750 5682.0 6.2 51 ° 52' 3619 24' 25" W. Gizeh . . . Khufu 4700 9068.8 .65 51 ° 52' 5776 3' 43" W. Khafra 4600 8474.9 1.5 530 I0' 5664 5' 26" W. Menkaura 4550 4153.6 3.0 51° lo' 2581 14' 3" E. Dahshur S.

. ? ? 7459.0 3.7 53° 5, 4134 9' 12" W. Dahshur Small . ? ? 2064.6 IT 440 34' 2034 16' 12" W. Both crystallize in the ditrigonal pyramidal (See also:

HEMIMORPHIC

hemimorphic-hemihedral) class of the See also:

RHOMBOHEDRAL

rhombohedral See also:

SYSTEM

system, possessing the same degree of symmetry as See also:

TOURMALINE

tourmaline. Crystals are perfectly See also:

DEVELOPED

developed and are usually prismatic in See also:

HABIT (through the French from Lat. habitus, from habere, to have, hold, or, in a reflective sense, to be in a certain condition; in many of the English senses the French use habitude, not habit)

habit; they are frequently attached at one end, the hemimorphic See also:

CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character being then evident by the fact that the oblique striations on the See also:

PRISM (Gr. rrpivµa, properly a thing sawn, Irpii"ety, to saw)

prism faces are directed towards one end only of the crystal. Twinning according to several See also:

LAWS

laws is not uncommon. The angles are nearly the same in the two species; the rhombohedral angle re' being 71° 22' in pyrargyrite and 72° 12' in proustite. The hexagonal prisms of pyrargyrite are usually terminated by a See also:

low hexagonal See also:

PYRAMID

pyramid (310) or by a drusy basal See also:

PLANE

plane. The See also:

COLOUR (Lat. color, connected with celare, to hide, the root meaning, therefore, being that of a covering)

colour of pyrargyrite is usually greyish-See also:

black and the lustre metallic-adamantine; large crystals are opaque, but small ones and thin splinters are deep ruby-red by transmitted light, hence the name, from Gr. See also:

alp (See also:

FIRE (in O. Eng. f j'r; the word is common to West German languages, cf. Dutch vuur, Ger. Feuer; the pre-Teutonic form is seen in Sanskrit pu, pavaka, and Gr. irup; the ultimate origin is usually taken to be a root meaning to purify, cf. Lat. purus)

fire) and &pyvpos (silver), given by E. F.

Glocker in 1831. The streak is purplish-red, thus differing markedly from the See also:

SCARLET

scarlet streak of proustite and affording a ready means of distinguishing the two minerals. The hardness is 22, and the specific gravity 5.85: the refractive indices and birefringence are very high, w=3.084, e=2.881. There is no very distinct cleavage and the fracture is conchoidal. The mineral occurs in metalliferous See also:

VEINS

veins with See also:

CALCITE

calcite, argentiferous See also:

GALENA

galena, native silver, native See also:

ARSENIC (symbol As, atomic weight 75.0)

arsenic, &c. The best crystallized specimens are from St Andreasberg in the Harz, See also:

FREIBERG, or FREYBERG

Freiberg in See also:

Saxony, and See also:

Guanajuato in See also:

Mexico. It is not uncommon in many silver mines in the See also:

UNITED

United States, but rarely as distinct crystals; and it has been found in some Cornish mines. Although the " red silver ores " afford a See also:

GOOD, JOHN MASON (1764-1827)

good example of isomorphism, they rarely See also:

FORM (Lat. forma)

form mixtures; pyrargyrite rarely contains as much as 30/s of arsenic replacing See also:

ANTIMONY (symbol Sb, atomic weight 120.2)

antimony, and the same is true of antimony in proustite. Dimorphous with pyrargyrite and proustite respectively are the rare See also:

MONOCLINIC

monoclinic species pyrostilpnite or fireblende (Ag3SbS3) and xanthoconite (Ag3AsS3) : these four minerals thus form an isodimorphous See also:

GROUP

group. (L. J.

End of Article: PYRARGYRITE

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