Beudantite | |
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![]() Large brown crystals of beudantite | |
General | |
Category | Arsenate minerals |
Formula (repeating unit) | PbFe3(OH)6SO4AsO4 |
IMA symbol | Bdn[1] |
Strunz classification | 8.BL.10 |
Dana classification | 43.4.1.1 |
Crystal system | Trigonal |
Crystal class | Hexagonal scalenohedral (3m) H-M symbol: (3 2/m) |
Space group | R3m |
Unit cell | a = 7.32 Å, c = 17.02 Å; Z = 3 |
Identification | |
Color | black, dark green, brown, yellowish, red, greenish yellow, brown |
Crystal habit | tabular, acute rhombohedral, pseudo-cubic, pseudo-cuboctahedral |
Cleavage | distinct; good on {0001} |
Mohs scale hardness | 3.5–4.5 |
Luster | vitreous, resinous |
Streak | grayish yellow to green |
Diaphaneity | transparent, translucent |
Specific gravity | 4.48 |
Optical properties | Uniaxial (−) |
Refractive index | nω = 1.957 nε = 1.943 |
Birefringence | δ = 0.014 |
Pleochroism | visible |
Other characteristics | Soluble 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
[edit]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
[edit]References
[edit]- ^ 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.
- ^ a b c Mindat.org
- ^ Web Mineral data
- ^ a b c Handbook of Mineralogy