Click here and add this page to your favorites!

|
Encyclopedia Britannica - Main :: PRE-PYR |
|
|
PYRARGYRITE , a mineral
Proust in 1804.From Vyse. 0 S 10 ISM / Place. King. Date B.C. Base. Error. Angle . Height. 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 ( hemimorphic
system
hemimorphic
laws
angle re' being 71 22' in pyrargyrite and 72 12' in proustite. The hexagonal prisms of pyrargyrite are usually terminated by a low hexagonal pyramid (310) or by a drusy basal plane. The colour of pyrargyrite is usually greyish-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. alp (fire) and &pyvpos (silver), given by E. F. Glocker in 1831. The streak is purplish-red, thus differing markedly from the 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
Guanajuato in Mexico
Although the " red silver ores " afford a good example of isomorphism, they rarely form mixtures; pyrargyrite rarely contains as much as 30/s of arsenic replacing antimony, and the same is true of antimony in proustite. Dimorphous with pyrargyrite and proustite respectively are the rare monoclinic species pyrostilpnite or fireblende (Ag3SbS3) and xanthoconite (Ag3AsS3) : these four minerals thus form an isodimorphous group. (L. J. S.) End of Article: PYRARGYRITE If you wish, you can link directly to this article.
<a href="http://jcsm.org/StudyCenter/Encyclopedia/PRE_PYR/PYRARGYRITE.html"> PYRARGYRITE </a> |
|
|
(Previous) PYRAMUS AND THISBE |
(Next) PYRAZINES, PIAZINES |
Jesus Christ Saves Ministries, P.O. Box 70696, Pasadena, CA 91117JCSM is a 501(c)(3), non-profit organization. Copyright © 1997-present. |
Free & Cheap Cell
Phones |
Cheap Long Distance
Phone Service Carriers |
Talk America Local Phone Service
|
Ztel & MCI - Unlimited Long Distance
Compare
Cell Phone Plans & Companies |
International Calling Cards & Prepaid Phone Cards |
Voice Over IP Broadband Internet Phone
Service | Wireless
Phone Plans & Cheap Cell Phones
|
_____________________________________________________________________________