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Formula: KNa2H(SO4)2
Sulphate
Crystal System: Monoclinic
Colour: Colourless, white
Environments
Kristjánite is a new mineral, approved in 2023 and to date (November 2024) reported only from the type locality.
Localities
At the type locality, the Magni crater, Fimmvörðuháls eruption site, Rangárþing eystra, Southern Region, Iceland,
kristjánite, was found in association with metathénardite,
belomarinaite, aphthitalite
and ivsite at a fumarole with a high temperature, greater than 600°C. The
kristjánite is most probably formed through a reaction between lava minerals
(sanidine and augite) and
SO2 and probably H2O from volcanic gas. It has a unique crystal structure containing
SO4–H–SO4 dimers featuring an almost straight linear and very short hydrogen bond, also observed
in some other A3H(SO4)2 compounds (where A stands for a large monovalent cation).
Kristjánite forms colourless transparent crystals up to ∼100 μm in size in compact aggregates with
metathénardite,
belomarinaite, aphthitalite,
ivsite and an unknown mineral with tentative composition
K2NaH(SO4)2, or growing in white globules of smaller grains on their surfaces
(MM 88.211–217)
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