Lautenthalite Explained

Formula:PbCu4(SO4)2(OH)6 · 3H2O
Imasymbol:Lth[1]
Strunz:07.DE.70
System:Monoclinic
Dana:31.06.01.02
Class:Prismatic
H-M symbol: (2/m)
Symmetry:P21/b
Unit Cell:2,799.47
Color:Blue green, green, greenish blue
Twinning:Polysynthetic on
Cleavage:Good on and, distinct
Mohs:2.5
Luster:Vitreous
Opticalprop:Biaxial (−)
Refractive:nα = 1.659(2)
nβ = 1.703(2)
nγ = 1.732(2)
Birefringence:0.073
Pleochroism:Weak
2V:78° – 79°
Dispersion:Strong, r < v
Streak:White
Gravity:3.84
Density:3.84
Diaphaneity:Transparent

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

Lautenthalite forms during the oxidation of copper, lead and zinc sulphides. 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

  1. Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3 . 291–320. 10.1180/mgm.2021.43 . 2021MinM...85..291W . 235729616 . free.
  2. Web site: Lautenthalite. 2021-08-08. www.mindat.org.
  3. Web site: Mineral Database. 2021-08-08. National Museum Wales. en.
  4. Lautenthalite, PbCu4[(OH)6/(SO4)2].3H2O, the Pb analogue of devillite. A new mineral from the Harz mountains, Germany . 1993. 99443180. Medenbach . O. . Gebert . W. . Neues Jahrbuch für Mineralogie - Monatshefte. 401–407.
  5. Web site: Lautenthalite Mineral Data. 2021-08-08. webmineral.com.