Betpakdalite-CaMg

Betpakdalite CaMg


Composition: [Ca2(H2O)17Mg(H2O)6][Mo8As2Fe3+3O36(OH)]
Crystal System : Monoclinic
Colours: Bright lemon-yellow
Lustre : Vitreous
Hardness (H) : 3
Specific Gravity (S.G) : 2.87
IMA Number: 2011-034
IMA Status: Approved
Discovered By: Not stated
Named for: Composition/relationship
References: Kampf et al. (2012)

 Tsumeb is the Type Locality

Distribution

Extremely rare. Type specimen is from 35 Level, second oxidation zone.

Occurrence

  • Supergene
  • 2nd Oxidation Zone

Notable Finds

As inclusions in scorodite, associated with quartz and djurleite, from 35 Level.

Paragenetic and General Notes

"Betpakdalite" (type locality in Kazakhstan) was recorded as a rare species at Tsumeb by Lombaard et al. (1986), but it was the reclassification of "betpakdalite", along with other members of the heteropolymolybdate family, by Kampf et al. (2012) that gave Tsumeb type locality status for the newly-defined species betpakdalite-CaMg.  Betpakdalite-CaMg occurs in association with (and as inclusions in) scorodite, with quartz and djureleite.  It is much rarer at Tsumeb than betpakdalite-CaCa.