|
See also:PYROPE (pronounced pirop) , a deep red variety of See also:garnet, named from the Gr. 7rvpw7r6r (fiery) in allusion to its See also:colour. It is used, like See also:almandine (q.v.), as a See also:gem-See also:- STONE
- STONE (0. Eng. shin; the word is common to Teutonic languages, cf. Ger. Stein, Du. steen, Dan. and Swed. sten; the root is also seen in Gr. aria, pebble)
- STONE, CHARLES POMEROY (1824-1887)
- STONE, EDWARD JAMES (1831-1897)
- STONE, FRANK (1800-1859)
- STONE, GEORGE (1708—1764)
- STONE, LUCY [BLACKWELL] (1818-1893)
- STONE, MARCUS (184o— )
- STONE, NICHOLAS (1586-1647)
stone, but may be distinguished by the See also:absence of any tinge of See also:violet in its colour and by its See also:lower specific gravity (3.7 or 3.8, while that of almandine is 4.1 to 4.3). The typical colour of pyrope is See also:blood-red, though sometimes a trace of See also:orange gives rise to a hyacinthine See also:hue: occasionally the See also:mineral becomes nearly See also:black, as seen in the pyrope of See also:Arendal in See also:Norway. Crystals are rare, but cubic forms have been observed. Pyrope may be regarded as a See also:magnesium-See also:aluminium garnet (see GARNET), but it usually contains more or less See also:calcium, See also:iron, See also:manganese and See also:chromium; and the See also:rich colour of the mineral seems due to the presence of some of the last three metals, though their exact See also:condition in the mineral has not been determined.
Pyrope generally occurs in grains embedded in peridotites (See also:olivine rocks) or in See also:serpentine resulting from their alteration, or it is foundthe earliest known is that of Homberg, prepared by See also:heating a mixture of See also:alum and finely divided See also:carbon to redness in a closed See also:tube. On opening the tube and emptying out the black See also:residue (consisting of See also:potassium sulphide, aluminium sulphate and carbon) it promptly catches See also:fire. Many readily oxidizable substances, especially when very finely divided, have the same See also:property. Metallic iron and See also:cobalt, when prepared under certain conditions, are pyrophoric, as is also ferrous See also:oxide. Spontaneously inflammable liquids are also known, e.g. certain alkyl metallic compounds, See also:phosphorus dihydride, &c.
End of Article: PYROPE (pronounced pirop)
Additional information and Comments
There are no comments yet for this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.
Links to articles and home page are always encouraged.
|
del.icio.us it!