PHYSICAL PROPERTIES:
Chemistry: PB5(VO4)5Cl
Composition: Lead chlorovanadate
Color: Bright red-brown-orange,
to yellow-brown, or brown
Class: Phosphates
Subclass:
Group: Apatite
Crystal system: hexagonal; 6/m
Crystal habit: typically the hexagonal
prism
with pinacoid as a termination. Rare crystals
can have the hexagonal pyramid as a termin-
ation. Can also be found as rounded masses
and crusts.
Fracture: conchoidal
Hardness: 2.75-3
Specific gravity: 6.7-7.1
Refractive Index: 2.39
Pleochroism:
Luster: resinous
Streak: yellowish white
Clevage: none, brittle
Transparency: transparent to translucent.
Associated Minerals: descloizite, wulfenite,
cerussite, and other secondary ore minerals
Environment:
Secondary, weathered, zone of lead ore deposits.
Crystal description:
Small six-sided prisms, and often in larger crystals in built-up masses
that are cavernous in the center. Pyramidal terminations only on slender
crystals.
Distinguishing characteristics:
It is separated from pyromorphite and mimetite by its blowpipe reactions.
Occurrence: Vanadinite is a secondary mineral forming in desert country
as a result of the alteration, by weathering. 0f lead ores. A unique
occurrence of very large crystals completely coated with descloizite
was found in South- west Africa.
Localities:
Numerous sites in Arizona and New Mexico. Among which the bright
orange-red crystals from the Old Yuma Mine near Tucson, Arizona, are
particularly well known. The orange skeletal crystals from Stein’s Pass
New Mexico, are also popular. A clear, light yellow arsenical variety
called endlichite is found at Hillsboro and Lake Valley, New Mexico.
More recently many wonderful Vanadinite
specimens have be coming from the M'Fis Mine near Mibladen Morocco.
Interesting Facts:
Though apparently abundant, vanadinite did not prove to be rich enough
in any southwestern occurrence to he workable as an ore during World
War II, when vanadium was much sought after.
Vanadinite shares the same structure with Apatite and the two share
similar crystal shapes at times. Vanadinite is part of a chemical series
with two other minerals; Pyromorphite (Pb5(PO4)3Cl) and Mimetite (Pb5(AsO4)3Cl).
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