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 Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
chlorophosphate:
Pb5(
P O4)
3 Cl, sometimes occurring in sufficient abundance to be mined as an
ore
Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...
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, macros ...
s are common, and have the form of a hexagonal prism terminated by the
basal plane
In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns th ...
s, 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
Mimetite is a lead arsenate chloride mineral (Pb5(AsO4)3Cl) which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name derives from the Greek Μιμητής ''mimetes'', meaning "imitator" a ...
(Pb
5(
AsO
4)
3Cl) and
vanadinite
Vanadinite is a mineral belonging to the apatite group of phosphates, with the chemical formula Pb5( V O4)3 Cl. It is one of the main industrial ores of the metal vanadium and a minor source of lead. A dense, brittle mineral, it is usually fou ...
(Pb
5(
VO
4)
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 fungus, fungi can form. The dust-like, colored appearance of molds is due to the formation of Spore#Fungi, spores containing Secondary metabolite#Fungal secondary metabolites, fungal seco ...
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
In mathematics, an isomorphism is a structure-preserving mapping between two structures of the same type that can be reversed by an inverse mapping. Two mathematical structures are isomorphic if an isomorphism exists between them. The word is ...
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 Ear ...
by 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, but ...
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 to ...
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
Bohemia ( ; cs, Čechy ; ; hsb, Čěska; szl, Czechy) is the westernmost and largest historical region of the Czech Republic. Bohemia can also refer to a wider area consisting of the historical Lands of the Bohemian Crown ruled by the Bohem ...
, nussierite from Nuizière, Chénelette
Chénelette () is a commune in the Rhône department in eastern France. While there have been settlements in the region since before the Roman conquest of Gaul, the modern village of Chénelette first appears in records dating to the 14th centur ...
, 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 France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, and cherokine from Cherokee County Cherokee County is the name of eight counties in the United States:
* Cherokee County, Alabama
* Cherokee County, Georgia
* Cherokee County, Iowa
* Cherokee County, Kansas
* Cherokee County, North Carolina
* Cherokee County, Oklahoma
* Cherokee Co ...
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 the ...
.
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 Gessner ...
crystals and crusts of contrasting, powder-blue caledonite
Caledonite, whose name derives from Caledonia, the historical name of its place of discovery (Scotland), is a richly colored blue-green sulfate-carbonate mineral of lead and copper with an orthorhombic crystal structure. It is an uncommon mineral ...
round out this very rich lead ore
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, l ...
specimen from an old Leadhills mine.
See also
* List of minerals
This is a list of minerals for which there are articles on Wikipedia.
Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various ''species''. Within a m ...
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