Formula:CaNaFe3+4(PO4)4(OH)3.5H2O
Hydrated phosphate containing hydroxyl
Crystal System: Triclinic
Specific gravity: 2.93 measured, 2.917 calculated
Hardness: 3
Streak: Yellow
Colour: Pale to golden yellow
Environments
Kapundaite is a rare phosphate.
At the type locality, Tom's Quarry, Kapunda, Mount Lofty Ranges, South Australia, kapundaite occurs as linings within cavernous masses
of an iron-rich phosphate rock (AJM 17.1.18). It is associated with
natrodufrénite, meurigite-Na,
leucophosphite (Mindat, AM 95.754-760),
wavellite and mitridatite;
fluellite and minyulite are rare associates
(AJM 17.1.18).
Kapundaite from Tom's Quarry - Image
The Emmons pegmatite, Uncle Tom Mountain, Greenwood, Oxford County, Maine, USA is complexly zoned with a wall zone
comprising K-feldspar, quartz,
almandine and schorl. The
intermediate zones comprise K-feldspar,
quartz, muscovite and altered
spodumene. A quartz-rich core is
present but is poorly exposed
(CM 56.543-553 2018).
Bright yellow crystals of kapundaite up to 1 mm in size have been discovered in the
secondary phosphate assemblages derived from the alteration of
lithiophilite. The crystals occur in a mineral assemblage dominated by
Fe3+-rich mineral species of strunzite,
jahnsite-group members,
kryzhanovskite, laueite,
pseudolaueite, stewartite,
beraunite, mitridatite and
strengite. The kapundaite
likely formed under oxidising conditions between 300°C and 100°C from primary phosphates of the
lithiophilite-triphylite
series. Initially, numerous species containing both Fe3+ and Mn2+ occur, such as
strunzite and stewartite, but
eventually the assemblages transform to essentially manganese-free species
such as strengite and
phosphosiderite, or species containing the alkali ions Na or K, such as
cyrilovite, leucophosphite or
kapundaite
(R&M 96.6.559-560).
Kapundaite from Emmons Quarry - Image
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