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
• METAL (through Fr. from Lat. metallum, mine, quarry, adapted from Gr. µATaXAov, in the same sense, probably connected with ,ueraAAdv, to search after, explore, µeTa, after, aAAos, other)

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
• GERMAN, DUTCH AND SCANDINAVIAN

German Rotgiiltigerz) was mentioned by G . See also:

• AGRICOLA (originally SCHNEIDER, then SCHNITTER), JOHANNES (1494-1566)
• AGRICOLA (the Latinized form of the name BAUER), GEORG (1490-1555)
• AGRICOLA, CHRISTOPH LUDWIG (1667-1719)
• AGRICOLA, GNAEUS JULIUS (A.D. 37-93)
• AGRICOLA, JOHANN FRIEDRICH (1720-1774)
• AGRICOLA, MARTIN (c. 1500-1556)
• AGRICOLA, RODOLPHUS (properly ROELOF HUYSMANN) (1443-1485)

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, ANTONIN (1832–1905)
• PROUST, JOSEPH LOUIS (1754–1826)

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
• KING (O. Eng. cyning, abbreviated into cyng, cing; cf. O. H. G. chun- kuning, chun- kunig, M.H.G. kiinic, kiinec, kiinc, Mod. Ger. Konig, O. Norse konungr, kongr, Swed. konung, kung)
• KING [OF OCKHAM], PETER KING, 1ST BARON (1669-1734)
• KING, CHARLES WILLIAM (1818-1888)
• KING, CLARENCE (1842–1901)
• KING, EDWARD (1612–1637)
• KING, EDWARD (1829–1910)
• KING, HENRY (1591-1669)
• KING, RUFUS (1755–1827)
• KING, THOMAS (1730–1805)
• KING, WILLIAM (1650-1729)
• KING, WILLIAM (1663–1712)

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, SETH (1850- )
• LOW, WILL HICOK (1853- )

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
• BLACK, ADAM (1784-1874)
• BLACK, JEREMIAH SULLIVAN (1810–1883)
• BLACK, WILLIAM (1841-1898)

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

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
• SAXONY (Ger. Provinz Sachsen)

Saxony, and See also:

• GUANAJUATO, or GUANAXUATO
• GUANAJUATO, or SANTA FE DE GUANAJUATO

Guanajuato in See also:

• MEXICO
• MEXICO (Span. Mejico, or Mexico,)
• MEXICO, FEDERAL DISTRICT OF
• MEXICO, GULF OF

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 .