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Formula: Na(UO2)(PO4).3H2O
Hydrated phosphate, uranyl mineral,
meta-autunite group
Crystal System: Tetragonal
Specific gravity: 3.62 calculated
Hardness: 2 to 2½
Colour: Lemon yellow
Luminescence: Fluoresces yellow green in short wave and long wave UV
RADIOACTIVE
Environments
Metanatroautunite is a secondary
uranium mineral
(Webmin).
Localities
At the Fairview Quarry, Robertstown, North Mt Lofty Ranges, Mt Lofty Ranges, South Australia,
metanatroautunite
occurs as crusts of thin platy crystals to 3 mm coating seams and lining cavities in phosphate rock. Associated
minerals include natrodufrénite and
cyrilovite
(AJM 17.1.20).
The Lake Boga granite, Lake Boga, Swan Hill Rural City, Victoria, Australia, is a very large intrusion formed about
365 million years ago. The entire outcrop of the granite is overlain
by sediments in places up to several hundred meters thick. The sole exposure into the
granite is the Lake Boga quarry, where the sediment is only a few
metres thick. The uppermost levels of the granite exhibit
aplite veins, pods of
pegmatite, and numerous miarolitic cavities, features that
are characteristic of the uppermost levels of a granite magma
intruded to shallow crustal levels.
(R&M 97.1.28-32).
Metanatroautunite from this locality
forms crystals and clusters to 4 mm across on limonite-coated joint planes
and in a miarolitic cavity in granite. Rare intergrowths with
saléeite and torbernite occur
(HOM, AJM 10.1.29-31).
Metanatroautunite from Lake Boga - Image
Boomerang Lake, Menangina Station, Menzies Shire, Western Australia, is a playa (flat area at the lowest part of
an undrained desert basin), situated in a semi-arid region with hot summers and mild winters. The playa forms part of
a chain of lakes that are usually dry, and there is surface water flow only after exceptional rains.
Metanatroautunite has been found in a small area close to the northern shore of the lake in saline,
gypsum-rich mud, mostly at depths of 30-100 cm. It appears as bright
greenish yellow disseminations, fracture coatings and veinlet infillings in the red-brown mud. Also present are
quartz, gypsum,
halite and a uranium oxide, probably
uraninite
(AM 66.1068-1072).
Metanatroautunite from Boomerang Lake -
Image
At the Kuruk U Deposit, Khodzhent, Sughd, Tajikistan, metanatroautunite occurs in the oxidised zone of a
uranium deposit in a granodiorite massif, associated with
schoepite, gypsum,
kaolinite and limonite
(HOM).
Metanatroautunite from Kuruk - Image
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