Formulae:
Betpakdalite-CaCa: [Ca2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O36(OH)]
Betpakdalite-CaMg: [Ca2(H2O)17Mg(H2O)6][Mo6+8As5+2Fe3+3O36(OH)]
Betpakdalite-FeFe: [Fe3+2(H2O)15(OH)2Fe3+(H2O)6][Mo6+8As5+2Fe3+3O37]
Betpakdalite-NaCa: [Na2(H2O)17Ca(H2O)6][Mo6+8As5+2Fe3+3O34(OH)3]
Betpakdalite-NaNa: [Na2(H2O)16Na(H2O)6][Mo6+8As5+2Fe3+3O33(OH)4]
These are arsenic-bearing
molybdates.
Specific gravity: 2.98 to 3.05
Hardness: 3 to 3½
Colour: Yellow
Environments
Localities
At its type locality, Mount Moliagul, Moliagul, Central Goldfields Shire, Victoria, Australia, betpakdalite-FeFe
is associated with ferrimolybdite and
muscovite as orange plates to 50 microns across in vugs in massive
quartz veins
(AJM 21.1.41).
The type locality for betpakdalite-NaNa is the Chuquicamata Mine, Chuquicamata District, Calama, El Loa Province,
Antofagasta, Chile.
In quartz vein outcrops, in the Knöttel area, Krupka, Ústí nad Labem Region,
Czech Republic, betpakdalite-CaCa occurs on vein quartz associated
with molybdenite, molybdite
and quartz
(HOM).
The type locality for betpakdalite-NaCa is the Kyzylsai Mo-U deposit, Chu-Ili Mountains, Moiynkum, Jambyl Region,
Kazakhstan.
At its type locality, the Kara-Oba W deposit, Betpakdala Desert, Karazhal, Karaganda Region, Kazakhstan,
betpakdalite-CaCa occurs in quartz -
hübnerite - pyrite -
arsenopyrite veins in the oxidised zone, associated with
ferrimolybdite, gypsum,
jarosite, muscovite variety illite,
limonite and opal
(AM 47.172, HOM, Dana).
At its type locality, the Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia, betpakdalite-CaMg crystals to 0.2 mm occur in
a deep oxidation zone of a dolostone-hosted hydrothermal polymetallic ore
deposit, singly or aggregated on scorodite and associated with
chalcocite, digenite and
quartz. It also occurs massive or as thin coatings, associated with
hematite, quartz,
scorodite, chalcocite,
powellite, kaolinite,
adamite, wulfenite,
hidalgoite and gerdtremmelite
(AM 70.1333, HOM, Dana).
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