Beudantite

Beudantite
Large brown crystals of beudantite
General
CategoryArsenate minerals
Formula
(repeating unit)		PbFe3(OH)6SO4AsO4
IMA symbolBdn[1]
Strunz classification8.BL.10
Dana classification43.4.1.1
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupR3m
Unit cella = 7.32 Å, c = 17.02 Å; Z = 3
Identification
Colorblack, dark green, brown, yellowish, red, greenish yellow, brown
Crystal habittabular, acute rhombohedral, pseudo-cubic, pseudo-cuboctahedral
Cleavagedistinct; good on {0001}
Mohs scale hardness3.5–4.5
Lustervitreous, resinous
Streakgrayish yellow to green
Diaphaneitytransparent, translucent
Specific gravity4.48
Optical propertiesUniaxial (−)
Refractive indexnω = 1.957 nε = 1.943
Birefringenceδ = 0.014
Pleochroismvisible
Other characteristicsSoluble in HCl
References[2][3][4]

Beudandite is a secondary mineral occurring in the oxidized zones of polymetallic deposits.[4] It is a lead, iron, arsenate, sulfate with endmember formula: PbFe3(OH)6SO4AsO4.

Beudantite is in a subgroup of the alunite group. It is the arsenate analogue of the phosphate corkite. Beudantite also forms a solid-solution with segnitite and plumbojarosite.[2]

It crystallizes in the trigonal crystal system and shows a variety of crystal habits including tabular, acute rhombohedral, pseudo-cubic and pseudo-cuboctahedral.

It occurs in association with carminite, scorodite, mimetite, dussertite, arseniosiderite, pharmacosiderite, olivenite, bayldonite, duftite, anglesite, cerussite and azurite.[4]

Discovery

Beudantite was first described in 1826 for an occurrence in the Louise Mine, Wied Iron Spar District, Westerwald, Rhineland-Palatinate, Germany. It was named by Armand Lévy after his fellow Frenchman and mineralogist François Sulpice Beudant (1787–1850).[2]

See also

References

Wikimedia Commons has media related to Beudantite.
  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c Mindat.org
  3. ^ Web Mineral data
  4. ^ a b c Handbook of Mineralogy