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Chemical Formula | Pb5(PO4)3Cl | ||
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Composition | Lead chloro-phosphate. The phosphate radical (PO4) may be partially replaced by an arsenate radical (AsO4), thus forming a series with Mimetite. | ||
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Variable Formula | Pb5([P,As]O4)3Cl | ||
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Color | Usually green to yellow-green, but also greenish-white, brownish-green, brown, orange, gray, and white. | ||
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Streak | White | ||
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Hardness | 3½ - 4 | ||
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Crystal Forms and Aggregates |
(Hexagonal) Occurs as barrel-like hexagonal crystals, which are usually grouped together in interesting aggregates, and may be bipyramidal. Also occurs as larger crystals, which are frequently hollow. Also acicular, crusty, grainy, radiating, reniform, and in curvy aggregates. | ||
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Transparency | Translucent | ||
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Specific Gravity | 6.9 - 7.1 (The hollow crystals must also be taken into account) | ||
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Luster | Resinous to greasy | ||
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Cleavage | None | ||
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Fracture | Subconchoidal to uneven | ||
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Tenacity | Brittle | ||
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Other Names |  Green Lead Ore |
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In Group | Phosphates ; True phosphates ; Apatite group | ||
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All About | Pyromorphite is a member of the Apatite group, a group of isomorphous hexagonal minerals. It is very similar in structure and appearance to Mimetite, and may be partially replaced by it. An intermediary member between Pyromorphite and Mimetite is called "Pyromorphite-Mimetite". | ||
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Uses | Pyromorphite is a minor ore of lead where it occurs with more abundant lead minerals. It is also a popular mineral among collectors. | ||
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Striking Features | Color, hollow crystals, crystal habits, and localities | ||
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Complex Tests | Dissolves in nitric acid | ||
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Popularity (1-4) | 2 | ||
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Prevalence (1-3) | 3 | ||
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Demand (1-3) | 1 | ||
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Distinguishing Similar Minerals |
Mimetite - Usually more yellow in color,
and less commonly occurs in hollow crystals. Otherwise
cannot be distinguished with practical methods Vanadinite - Usually more red in color, has a slightly yellow streak, and is slightly softer. Otherwise cannot be distinguished with practical methods Apatite - Harder (5) |
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Commonly Occurs With |
Limonite, Galena, Barite, Vanadinite, Cerussite, Wulfenite, Hemimorphite | ||
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Noteworthy Localities |
There are many fine Pyromorphite localities
worldwide. Excellent specimens come from Cornwall,
England; Bad Ems, Nassau, Germany; El Horcajo, Spain;
Pribam, Czech Republic; Beresovsk, Ural Mountains,
Russia; Broken Hill, Zambia; and Broken Hill, New South
Wales, Australia. Light green crystals associated with Wulfenite comes from Mapimi, Durango, Mexico. In Canada, specimens were found in the Society Girl claim in the Steel District, British Columbia. In the U.S., the finest specimens are from the Bunker Hill Mine in the Coeur d'Alene District, Shoshone Co., Idaho. The Wheatley Mines in Phoenixville, Chester Co., Pennsylvania produced some famous and old-time examples, and good crystals were found in Davidson Co., North Carolina. |
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Picture Icon Links |
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Picture Links | 1. Hexagonal Pyromorphite "barrels" |
