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Lautenthalite

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Lautenthalite
General
CategoryMineral
Formula
(repeating unit)
PbCu4(SO4)2(OH)6 · 3H2O
IMA symbolLth[1]
Strunz classification07.DE.70
Dana classification31.06.01.02
Crystal systemMonoclinic
Crystal classPrismatic
H-M symbol: (2/m)
Space groupP21/b
Unit cell2,799.47
Identification
ColorBlue green, green, greenish blue
TwinningPolysynthetic on {100}
CleavageGood on {001} and {010}, distinct
Mohs scale hardness2.5
LusterVitreous
StreakWhite
DiaphaneityTransparent
Specific gravity3.84
Density3.84
Optical propertiesBiaxial (−)
Refractive indexnα = 1.659(2)
nβ = 1.703(2)
nγ = 1.732(2)
Birefringence0.073
PleochroismWeak
2V angle78° – 79°
DispersionStrong, r < v

Lautenthalite is a mineral that was named after its location, Lautenthal, Harz mountains, Germany. It can be found in several slag localities. It was approved by the IMA in 1993. It is a member of the devilline group, and it is the lead analogue of devilline and campigliaite. Without analytical methods, it is hard to distinguish the mineral from both. It shows pleochroic properties, which is an optical phenomenon. Depending on which angle the mineral is inspected, the color of it differs. On the x optical axis, the mineral could be seen in a pale blue color; on the y and z axis, the mineral's color changes to blue. It has tabular crystals and sheaflike or irregular aggregates.[2] Lautenthalite is associated with wroewolfeite, which it tends to overgrow. It is also associated with anglesite, devilline–serpierite, galena, linarite, brochantite and schulenbergite.[3] It forms small singular crystals with a size of up to 0.5 × 0.3 × 0.03 mm.[4]

Chemical properties

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Lautenthalite forms during the oxidation of copper, lead and zinc sulphides.[3] It mostly consists of oxygen (33.60%), copper (31.40%) and lead (25.59%), but also contains sulfur (7.92%) and hydrogen (1.49%).[5]

References

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  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. ^ "Lautenthalite". www.mindat.org. Retrieved 2021-08-08.
  3. ^ a b "Mineral Database". National Museum Wales. Retrieved 2021-08-08.
  4. ^ Medenbach, O.; Gebert, W. (1993). "Lautenthalite, PbCu4[(OH)6/(SO4)2].3H2O, the Pb analogue of devillite. A new mineral from the Harz mountains, Germany". Neues Jahrbuch für Mineralogie - Monatshefte: 401–407. S2CID 99443180.
  5. ^ "Lautenthalite Mineral Data". webmineral.com. Retrieved 2021-08-08.