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Formula: K3Zn2Cl7
Chloride, zinc-bearing mineral
Crystal System: Triclinic
Specific gravity: 2.46 measured, 2.49 calculatedfor the empirical formula
Hardness: ~2
Streak: Yellow
Colour: Yellow-brown to reddish brown
Solubility: Soluble in water
Common impurities: Cu,Mg,(Rb)
Environments
Mellizinkalite is a relatively new mineral, approved in 2014 and to date (March 2025) reported only from the
type locality.
Localities
At the type locality, the Glavnaya Tenoritovaya fumarole, Second scoria cone, Northern Breakthrough, Great Fissure
eruption, Tolbachik Volcanic field, Milkovsky District, Kamchatka Krai, Russia, specimens with mellizinkalite
were collected in July 2013 from the second scoria cone, formed in 1975. The Glavnaya Tenoritovaya fumarole is located
in the western wall of a big contraction fracture cross-cutting the top of the scoria cone. Gas vents belonging to this
fumarole occupy an area of 1.7 x 4.2 m2. The main part of this area is at temperatures of 350 to
360oC, measured at about 20 cm depth. Major minerals formed in this zone are sulphates
(euchlorine, dolerophanite,
chalcocyanite, anglesite,
krasheninnikovite and
anhydrite), hematite and
tenorite. The rich chloride mineralisation was observed only in an outer,
moderately hot (110oC) zone in the northern flank of the fumarole. The area in which chlorides are
concentrated is a lenticular body about 1.5 m long and up to 0.2 m thick. These minerals are represented by
belloite, avdoninite,
eriochalcite, sylvite,
halite, carnallite,
mitscherlichite, sanguite,
chrysothallite,
romanorlovite, mellizinkalite,
flinteite and an incompletely studied K-Pb-Cu hydroxychloride. Other
minerals are gypsum,
chlorothionite, kainite and
earlier hematite, tenorite and
chalcocyanite. Unlike the hottest oxide–sulphate zone
(350 to 360oC) in which only anhydrous minerals are present, in this sulphate–chloride zone OH- and
H2O-bearing minerals are abundant.
Mellizinkalite is one of the last minerals to form in the assemblage. It was found in small amounts only in
cavities of the chloride and sulphate–chloride incrustations. Mellizinkalite mainly occurs as equant, elongated
or flattened, irregularly shaped grains up to 0.5 mm across, their clusters, groups or granular crusts up to
2 x 2 mm2 in area and up to 0.5 mm thick. Individual crystals of the mineral typically have smooth
contours. Crude acicular crystals and anthodites (cave formations composed of long needle-like crystals situated in
clusters which radiate outward from a common base) of mellizinkalite up to 1.3 mm long and up to 0.25 mm thick,
sometimes strongly twisted or curled, were also observed.
Mellizinkalite is yellow-brown to reddish brown, typically honey- or cognac- coloured with a yellow streak. It is
transparent, with a vitreous lustre
(EJM 27.2.247-253).
Mellizinkalite from the Glavnaya Tenoritovaya
Fumerole - Image
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