Pyromorphite is a mineral species composed of lead chlorophosphate: Pb<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>Cl, 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.

Pyromorphite is part of the apatite group of minerals and bears a close resemblance physically and chemically with two other minerals: mimetite (Pb<sub>5</sub>(AsO<sub>4</sub>)<sub>3</sub>Cl) and vanadinite (Pb<sub>5</sub>(VO<sub>4</sub>)<sub>3</sub>Cl). 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).

History

The mineral 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.

Biology

Paecilomyces javanicus is a fungus collected from a lead-polluted soil that is able to form biominerals of pyromorphite.

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File:Pyromorphite-137773.jpg|A pocket of crystals of pyromorphite from China

File:Pyromorphite-157594.jpg|Miniature of sharp, lustrous, apple green color crystal "sprays" on matrix

File:Pyromorphite-137954.jpg|Fine crystals of pyromorphite from Daoping Mine, Guangxi Zhuang Autonomous Region, China

File:Pyromorphite-118273.jpg|Green pyromorphite crystals densely carpet the display side of the large matrix

File:Pyromorphite-Cerussite-Caledonite-278353.jpg|Green pyromorphite microcrystals cover the vuggy, quartz-rich matrix. Seams of tiny cerussite crystals and crusts of contrasting, powder-blue caledonite round out this very rich lead ore specimen from an old Leadhills mine.

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See also

  • Lead apatite
  • List of minerals

References