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Formula: Na2Mg(SO4)2.5H2O
Hydrated sulphate
Crystal System: Monoclinic
Specific gravity: 2.088 measured, 2.097 calculated
Hardness: 2½
Streak: White
Colour: White, Colourless
Luminescence:
Solubility: Very easily soluble in water, unstable - alters to blödite in a
relatively short period of time
Environments
Hydrothermal environments
Cave deposits
Konyaite is widespread in salt efflorescences on saline soils, formed between 30◦C and 50◦C by evaporation of
ground and surface waters. Associated minerals include gypsum,
hexahydrite, blodite,
halite, starkeyite,
löweite, mirabalite,
thénardite, epsomite,
burkeite and tychite
(HOM).
Localities
At the Kukla mine, Oslavany, Brno-Country District, South Moravian Region, Czech Republic, several stages of development
of the burning waste piles characterised by distinct mineral assemblages have been distinguished, namely (1) a
high-temperature stage of active burning, (2) a cooling stage and (3) a stage of recent evaporation.
Typical features of the high-temperature stage are pyrometamorphic products
(paralavas, clinkers) and gas exhalation products. Large parts of the
pile material were transformed into hematite-rich silicate glass
paralavas and potassic
(feldspar-bearing) clinkers with
corundum, cristobalite and rare
lechatelierite. Hematite-rich
paralavas commonly form thin flows, coatings, and stalactites with
velvet lustre; their cores are formed of aluminous glass with abundant microscopic (less than 10 μm in size)
Al-hematite, spinel and
corundum, whereas the margins consist of
hematite crystals larger than 100 μm in size). Compositions of
Al-hematite and corundum indicate
their origin at a temperature of ~ 1100°C. During active burning of the material,
sulphur, salammoniac,
letovicite, tschermigite,
mascagnite, thénardite,
metavoltine and other phases formed from gas exhalations.
Cooling stage mineral assemblages are mainly characterised by aragonite,
calcite (at depths greater than 10 cm),
anhydrite and gypsum (near surface).
In this stage, sulphur oxidation took place and dissolved sulphate anions reacted with the pile material, and
substantial amounts of Ca and Mg were released from the sedimentary rocks on the pile. The Oslavany pile typically
lacks recently precipitating Fe-sulphates (only rare
magnesiocopiapite was found).
After complete cooling of the pile, evaporation and crystallisation from solutions at low temperature became
significant mineralising factors. Hexahydrite dominates among sulphates;
epsomite, pentahydrite,
starkeyite, kieserite,
picromerite, konyaite,
alum-(K) and tamarugite are rare
and their occurrences strongly depend on temporal changes of moisture and temperature
(CM 51.1.171–188).
At Avion, Lens, Pas-de-Calais, Hauts-de-France, France, a coal-waste heap that has been undergoing subsurface
combustion for several decades is marked by the occurrence of efflorescences at combustion sites where gas and water
vapour escape from surficial cracks and vents. Twenty different mineral species are present in the efflorescences,
comprising various sulphates, halides and native sulphur. The constituents
needed for the formation of these minerals are ultimately derived from the heap of coal mine waste, composed mainly of
pyrite-bearing carbonaceous shale,
coal and minor amounts of sandstone. They may be partly released by
acid weathering of waste-heap materials prior to combustion, but largely by thermal decomposition and oxidation of those
materials during combustion processes. Formation of the efflorescences near gas-discharge zones indicates transport of
constituents to those zones from the inner part of the waste heap, which can occur in the gas phase for some elements
(S, N, H and Cl), but would require droplets of water vapour as carriers for most cations. Interaction between
condensate solutions and the local debris at the surface of the waste heap may also contribute to cations input prior to
the formation of secondary minerals.
Most minerals formed from a liquid phase along the rock-debris surface at temperatures less than 100°C, as confirmed by
the occurrence of fluid inclusions. Only salammoniac,
native sulphur and
mascagnite (where crystallised as a monocrystalline phase) were formed
directly from a gas phase. Secondary minerals present include
alunogen, aphthitalite,
arcanite, blödite,
epsomite, glauberite,
gypsum, halite,
halotrichite, hexahydrite,
kalinite, konyaite,
langbeinite, lecontite,
mascagnite, pickeringite,
salammoniac, suphur,
thénardite and tschermigite
(CM 47.573-591).
Tăușoare Cave, Bistrița-Năsăud County, Romania, is renowned for its gypsum and
mirabilite speleothems (cave formations). The collected samples reveal
crystals of two different habits. One shows the characteristic mirabilite
fibrous crystals (cotton-like speleothem) while the other formed bladed and short prismatic crystals which comprise the
delicate ‘cave flowers’. Besides thénardite (dehydration product of
mirabilite) other minerals that were identified included the sulphates
leonite, syngenite and
konyaite
(MM 65.1.103–109).
At the type locality, Cakmak, Ereğli District, Konya Province, Turkey, konyaite has been found in salt
effiorescences on saline soils. The Great Konya Basin has no natural outlet, and most rivers flowing into the basin
come from the Taurus mountains. Salts originate at the soil surface by evaporation of ground and surface waters.
Konyaite occurs in the efflorescences in the following assemblages:
(1) konyaite, gypsum,
hexahydrite and blödite
(2) konyaite, blödite, halite
and starkeyite
(3) konyaite, blödite, gypsum
and halite
(4) konyaite, gypsum and
hexahydrite
(5) konyaite, löweite, and
hexahydrite
(AM 67.1035-1038).
Konyaite from the Great Konya Basin - Image
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