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Formula: Pb6Cr(Cl,OH)6(OH,O)8
Valence: Pb2+6Cr3+Cl6O(OH)7
Chloride, Chromium-bearing mineral
Crystal system: Trigonal
Specific gravity: 5.85 measured, 5.8 calculated
Hardness: 2½
Streak: White
Colour: Red-violet
Luminescence: Not fluorescent under UV
Environments
Although yedlinite was approved in 1974, to date (May 2026) it has been reported only from the type locality.
Localities
At the type locality, the Mammoth-Saint Anthony Mine, St. Anthony deposit, Tiger, Mammoth Mining District, Pinal County,
Arizona, USA, yedlinite is found sparingly on a few specimens. It is associated with the most complex paragenesis
yet observed in Mammoth Mine material. Minute, doubly-terminated quartz crystals,
which replaced primary galena, formed a
framework for deposition of diaboleite. This was later relaced by
phosgenite and rarely matlockite,
and altered to wherryite. Yedlinite crystals are commonly found growing
upon and partly surrounded by diaboleite or in intimate contact with
phosgenite. Wulfenite,
dioptase, cerussite,
mimetite, willemite,
hemimorphite, fluorite and
quartz were later superimposed. Yedlinite is observed rarely perched on
dioptase and among the fluorite and
drusy quartz. Crystals of other minerals are never observed to be implanted on
yedlinite. A little earthy hematite is present occasionally.
Chromium, essential to yedlinite, is apparently an extremely minor
element in the Mammoth Mine ores. Exceptional fornacite crystals are rarely
locally abundant. Crocoite has been reported. Sparsely occurring yellow-green
cerussite and wherryite, yellow
leadhillite and brilliant red
wulfenite may owe their colour to this element.
Crystals of yedlinite are transparent to translucent hexagonal prisms up to about one millimeter in length. The
colour is red-violet, and may vary both in hue and intensity within a single crystal. The streak is white. The Mohs'
scale hardness is about two and a half, and the mineral is generally not brittle and somewhat sectile
(AM 59.1157-1159).
Yedlinite is a very rare late-stage secondary mineral in
the oxidised polymetallic hydrothermal ore deposit
(HOM).
Yedlinite from the Mammoth-Saint Anthony Mine -
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