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Formula: Fe(SO4).H2O
Hydrated sulphate, kieserite group, forms a complete solid solution with
kieserite
Crystal System: Monoclinic
Specific gravity: 3.03 to 3.07 measured, 3.10 calculated
Hardness: 2½
Streak: White
Colour: Bluish, colourless, yellow, yellow-brown, light blue
Solubility: Dissolves in water very slowly
Common impurities: Cu,Co
Environments
Hydrothermal environments
Martian environments
Szomolnokite is an uncommon secondary mineral formed
in pyrite-rich oxidised sulphide deposits, typically under highly acid and
arid conditions. Associated minerals include rhomboclase,
halotrichite,
fibroferrite,
römerite, copiapite,
voltaite and pyrite
(HOM).
Localities
At the Santa Elena Mine, Quebrada Alcaparrosa, Calingasta, Calingasta Department, San Juan Province, Argentina,
szomolokite is associated with copiapite
(Dana).
At the Alcaparrosa Mine, Cerritos Bayos, Calama, El Loa Province, Antofagasta, Chile, szomolokite is
associated with
römerite and
rhomboclase
(Dana).
At the El Indio deposit, Elqui Province, Coquimbo, Chile, the host rocks consist mainly of
granite and breccia
pipes.
Hydrothermal activity produced two stages of alteration in which four types of mineralisation are recognised,
based on the occurrence of economic concentrations of gold in rocks
containing significant amounts
of the following minerals:
(1) alunite, pyrite and
enargite
(2) pyrite
(3) pyrite and szomolokite
(4) native gold
Main-stage gold mineralisation was followed by a sulphate stage represented
by baryte and anglesite at
lower elevations
and baryte, anglesite and
primary szomolokite, the first reported occurrence
of this
phase as a hydrothermal ore mineral, at higher elevations. Late-stage
silver
mineralisation enriched the upper parts of the deposit
(EG 100.3.463-490).
At the type locality, Smolník, Gelnica District, Košice Region, Slovakia, szomolokite is associated with
rhomboclase
(Dana).
At the Rio Tinto Mines, Minas de Riotinto, Huelva, Andalusia, Spain, the soluble metal sulphate salts
melanterite, rozenite,
rhomboclase, szomolokite,
copiapite, coquimbite,
hexahydrite and
halotrichite,
together with gypsum, have been identified.
Secondary iron
sulphate minerals can form directly from evaporating, acid, sulphate-rich solutions as a result of
pyrite oxidation. Melanterite
and rozenite precipitates at Río Tinto are only found in association
with very acidic
drainage waters (pH <1.0), draining directly from pyritic waste piles.
Copiapite precipitates abundantly by direct evaporation of the river
water, or as part of a paragenetic sequence with the inclusion of minor
halotrichite
(MM 67.2.263-268).
At the Dolliver Memorial State Park, Iowa, USA, abundant sulphate efflorescences on
sandstone consist of
halotrichite,
szomolokite and rozenite.
Melanterite may occur in place of the lower hydrate,
rozenite, during times of high humidity
(CM 11.958).
At the North Mesa 5 Mine, Temple Mountain, San Rafael Mining District, Emery county, Utah, USA, szomolokite
is associated with bobjonesite
(Minrec 35.4.344).
On the surface of Mars, kieserite is a dominant sulphate species at
lower latitudes. However, given the
iron-rich composition of the Martian surface, it is very probable that its
actual composition lies at an intermediate value along the solid-solution series between the
kieserite and szomolokite end-members. The existence of a
continuous
kieserite–szomolokite solid-solution series on the Martian
surface is proved
(AM 104.1732-1749).
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