Pyromorphite is a

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ...

species composed of

lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate ...

chlorophosphate: Pb₅( P O₄)₃ Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead.

Crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macr ...

s 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. '' Paecilomyces javanicus'' is a

mold A mold () or mould () is one of the structures certain fungi can form. The dust-like, colored appearance of molds is due to the formation of spores containing fungal secondary metabolites. The spores are the dispersal units of the fungi. Not ...

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

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 Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

6.5 - 7.1. Owing to isomorphous replacement of the

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...

arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, bu ...

there may be a gradual passage from pyromorphite to mimetite. Varieties containing

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

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 Stříbro (pronounced ''Mies'' in German) in Bohemia, nussierite from Nuizière,

Chénelette Chénelette () is a Communes of France, commune in the Rhône (department), Rhône Departments of France, department in eastern France. While there have been settlements in the region since before the Roman conquest of Gaul, the modern village of ...

, near Beaujeu,

Rhône The Rhône ( , ; wae, Rotten ; frp, Rôno ; oc, Ròse ) is a major river in France and Switzerland, rising in the Alps and flowing west and south through Lake Geneva and southeastern France before discharging into the Mediterranean Sea. At Ar ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan ar ...

, and cherokine from Cherokee County in

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to t ...

Gallery

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 Cerussite (also known as lead carbonate or white lead ore) is a mineral consisting of lead carbonate (PbCO3), and is an important ore of lead. The name is from the Latin ''cerussa'', white lead. ''Cerussa nativa'' was mentioned by Conrad Gess ...

crystals and crusts of contrasting, powder-blue caledonite round out this very rich lead ore specimen from an old Leadhills mine.

References

External links

*{{1911, wstitle=Pyromorphite, volume=22, pages=693–694 Lead minerals Phosphate minerals Halide minerals Hexagonal minerals Minerals in space group 176 Luminescent minerals

Properties and isomorphism

Gallery

See also

References

External links