Images
Formula: Na2(SO4)
Anhydrous sulphate, paramorph of
thénardite
Crystal System: Hexagonal
Specific gravity: 2.72 measured, 2.717 calculated
Hardness: 3
Streak: White
Colour: Colourless, white, light blue, greenish, yellowish, greyish or brownish
Solubility: Dissolves in water at room temperature
Environments
Metathénardite is a high-temperature, hexagonal mineral approved in 2016. All specimens with
metathénardite were collected from areas with temperatures of 350 to 400°C
(Mindat).
Localities
There are three co-type localities, the Arsenatnaya fumarole, the Glavnaya Tenoritovaya fumarole, and the
Yadovitaya fumarole, all at the Second scoria cone, Northern Breakthrough, Great Fissure eruption, Tolbachik
Volcanic field, Milkovsky District, Kamchatka Krai, Russia.
The holotype specimen was found in the Glavnaya Tenoritovaya fumarole; later the mineral was identified in several
other Tolbachik fumaroles. It is a common sulphate mineral in high-temperature exhalations of the three active
fumaroles Glavnaya Tenoritovaya, Yadovitaya and Arsenatnaya. Metathénardite samples from the Yadovitaya and
Arsenatnaya fumaroles that are considered to be cotypes. Specimens with metathénardite were collected from
hot zones of all three fumaroles. The temperatures in these areas varied from 350 to 400oC.
The holotype metathénardite from the Glavnaya Tenoritovaya fumarole is associated with
hematite, tenorite,
fluorophlogopite,
sanidine, anhydrite,
krasheninnikovite,
vanthoffite, glauberite,
johillerite and lammerite.
The secondary, supergene association includes
gypsum, blödite, and powdery
aggregates of unidentified sulphates. At this location the metathénardite occurs as interrupted crusts up to
2 x 2 cm2 in area and up to 0.2 mm thick overgrowing basalt
scoria or thin incrustations of
fluorophlogopite and
hematite covering the surface of
basalt
scoria. The crystals and grains of metathénardite forming the
crust commonly contain abundant dust-like inclusions of hematite.
The cotype from the Arsenatnaya fumarole is typically associated with
hematite, tenorite,
fluorophlogopite, sanidine,
euchlorine, wulffite,
anhydrite, fluoborite,
johillerite, nickenichite,
calciojohillerite,
badalovite, tilasite,
cassiterite and
pseudobrookite. At this locality the metathénardite forms
abundant crystal crusts and brushes up to several hundred cm2 in area, typically open-work, in cavities
between blocks of basalt
scoria and volcanic bombs. The crystals are up to 3 mm across and up
to 1 mm thick.
The cotype metathénardite from the Yadovitaya fumarole is associated with
tenorite, euchlorine,
fedotovite, dolerophanite,
langbeinite,
krasheninnikovite,
anhydrite and hematite.
Metathénardite here is a widespread mineral forming clusters, incrustations, and brushes up to
20 cm2 in area of hexagonal tabular crystals
(CM 57.6.885-901).
Back to Minerals