RockHoundLounge Forum › RockHoundLounge General › Mineral of the Month › Pyromorphite - November 2015
‹ Previous Topic | Next Topic ›
Page Index Toggle Pages: 1 Send TopicPrint
Normal Topic Pyromorphite - November 2015 (Read 1388 times)
Scott LaBorde
RHL Administrator
*****
Offline


"Rock it" science!

Posts: 2971
Location: Wake Forest, NC
Joined: Sep 28th, 2010
Gender: Male
Pyromorphite - November 2015
Nov 5th, 2015 at 8:11am
Print Post  
Pyromorphite is a mineral species composed of lead chlorophosphate: Pb5(PO4)3Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead. Crystals are common, and have the form of a hexagonal prism terminated by the basal planes, sometimes combined with narrow faces of a hexagonal pyramid. Crystals with a barrel-like curvature are not uncommon. Globular and reniform masses are also found. It is part of a series with two other minerals: mimetite (Pb5(AsO4)3Cl) and vanadinite (Pb5(VO4)3Cl), the resemblance in external characters is so close that, as a rule, it is only possible to distinguish between them by chemical tests.
They were formerly confused under the names green lead ore and brown lead ore (German: Grünbleierz and Braunbleierz). The phosphate was first distinguished chemically by M. H. Klaproth in 1784, and it was named pyromorphite by J. F. L. Hausmann in 1813. The name is derived from the Greek for pyr (fire) and morfe (form) due to its crystallization behavior after being melted.

Properties and isomorphism
The color of the mineral is usually some bright shade of green, yellow or brown, and the luster is resinous. The hardness is 3.5 to 4, and the specific gravity 6.5 - 7.1. Owing to isomorphous replacement of the phosphorus by arsenic there may be a gradual passage from pyromorphite to mimetite. Varieties containing calcium isomorphously replacing lead are lower in density (specific gravity 5.9 - 6.5) and usually lighter in color; they bear the names polysphaerite (because of the globular form), miesite from Mies in Bohemia, nussierite from Nuizière, Chénelette, near Beaujeu, Rhône, France, and cherokine from Cherokee County in Georgia.

Soure Wikipedia page:  https://en.wikipedia.org/wiki/Pyromorphite
  
2015-11-05_0811.png ( 136 KB | 134 Downloads )
2015-11-05_0811.png
Scott LaBorde
RockHoundLounge Creator
Back to top
WWWYouTube  
IP Logged
 
Page Index Toggle Pages: 1
Send TopicPrint
‹ Previous Topic | Next Topic ›
 
  « Board Index ‹ Board Top  

RockHoundLounge Forum » Powered by YaBB 2.6.11!
YaBB Forum Software © 2000-2024. All Rights Reserved.

Valid RSS Valid XHTML Valid CSS Powered by Perl Source Forge