- Pyromorphite
Infobox mineral
name = Pyromorphite
category = Mineral
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caption = Yellow pyromorphite fromAustralia
formula = Pb5(PO4)3Cl
molweight = 1,356.37 gm
color = Colorless, Green, Yellow, etc...
habit = massive to crystaline
system = Hexagonal
twinning =
cleavage = Imperfect- [1011]
fracture = Brittle
tenacity = Brittle
mohs = 3.5-4
luster =vitreous
polish =
refractive =
opticalprop =
birefringence =
dispersion =
pleochroism =
fluorescence= None
absorption =
streak = White
gravity =
density = 7.109 g/cm3
melt =
fusibility =
diagnostic =
solubility =
diaphaneity = Transparent to opaque
other =
references =Pyromorphite is a
mineral species composed oflead chlorophosphate: Pb5(PO4)3Cl, sometimes occurring in sufficient abundance to be mined as anore of lead.Crystal 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) andvanadinite (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. Kiaproth in 1784, and it was named pyromorphite by J. F. L. Hausmann in 1813.
The color of the mineral is usually some bright shade of green, yellow or brown, and the luster is resinous. The hardness is 3, and the
specific gravity 6.5 - 7.1. Owing to isomorphous replacement of thephosphorus byarsenic there may be a gradual passage from pyromorphite to mimetite. Varieties containingcalcium 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 fromMies inBohemia , nussierite fromNuizière ,Chénelette , near Beaujeu, Rhône,France , and cherokine from Cherokee County in Georgia.See also
*
List of minerals References
*1911
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