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Formula: PbFe3+3(AsO4)(SO4)(OH)6
Compound arsenate,
beudantite group,
alunite supergroup
Crystal System: Trigonal
Specific gravity: 4.48 measured, 4.49 calculated
Hardness: 3½ to 4½
Streak: Black to grey
Colour: Dark green, brown, black
Solubility: Soluble in hydrochloric acid
Common impurities: Al,P
Environments
Beudantite is a secondary mineral occurring in
the oxidised zones of
polymetallic deposits. Some beudantite may
contain minor antimony replacing iron
(Mindat).
Localities
At the Clara Mine, in the Black Forest, Germany, beudantite is common, lining cavities in
baryte or quartz, and associated with
segnitite, kintoreite,
corkite and dussertite
(R&M 90.1.40).
At Burdell Gill, Cumbria, England, UK, beudantite is uncommon, but it sometimes occurs on
baryte or quartz associated with
mimetite and carminite
(JRS 8(1).4).
At Roughton Gill, Cumbria, England, UK, beudantite occurs as crusts on
quartz, and
also in cellular quartz veinstone, with
baryte and lepidocrocite. It is
sometimes associated with carminite
(JRS 11.8).
At Sandbed, Cumbria, England, UK, beudantite occurs as a encrustation on
mimetite
with scorodite and
pharmacosiderite. A mineral intermediate between beudantite
and segnitite occurs in cavities in
quartz, apparantly formed by the oxidation of
primary
arsenopyrite
(JRS 9.15).
At Short Grain, Cumbria, England, UK, beudantite occurs on quartz or
baryte associated with mimetite,
arseniosiderite and
carminite. It sometimes forms
pseudomorphs after
mimetite. Other associates include
supergene
baryte and
bariopharmacosiderite
(JRS 12.51).
At Silver Gill, Cumbria, England, UK, beudantite occurs coating
mimetite crystals
(JRS 8(2).89).
At the San Rafael Mine, Nevada, USA, beudantite occurs in boxwork limonite associated with
segnitite, mimetite and
adamite, and also within
quartz-lined vugs.
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