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K2MgCa2(SO4)4·2H2O A sulfate mineral usually found in fibrous brick-red masses due to iron.



a mineral, a hydrated sulfate of potassium, calcium, and magnesium with composition K2Ca2Mg[SO4]4 · 2H2O. It contains 15.62 percent K2O, 18.60 percent CaO, 6.69 percent MgO, 53.11 percent SO3, and 5.98 percent H2O. Polyhalite crystallizes in the triclinic system, forming granular aggregates and, more rarely, fibrous or columnar aggregates. Tabular and elongated crystals with distinct cleavage are rare. Polyhalite is colorless, gray, pink, or brick-red. It has a hardness of 2.5–3.5 on Mohs’ scale and a density of 2,720–2,780 kg/m It decomposes upon the action of water to precipitate gypsum.

Polyhalite is widely distributed in commercial salt deposits, where it is most often associated with rock salt and anhydrite, as well as with sylvite, carnallite, and kieserite. It may be used in the preparation of potassium fertilizers.

References in periodicals archive ?
Uni-axial compressive strength for the polyhalite, as well as minerals above and below the ore line and
The polyhalite will be transported from the North York Moors National Park via a 45km underground pipeline to a processing plant in Teesside, so noisy and polluting lorry traffic will not have to trundle through the country lanes.
About 6 meters above the ceiling, the drill hit a thin polyhalite bed, then broke into a large cavity, and brine rushed out.
The Salado Formation, or main salt, consists of thick halite intervals with interbedded anhydrite, siltstone and polyhalite.
The new harbour facilities in Teesside will be the export facility for polyhalite to be mined from a new mine to be constructed near Whitby, North Yorkshire which will be linked to the material handling facility by way of a 37km long tunnel.
Project development includes an underground transport system to convey mined polyhalite 37.
On Monday it announced a memorandum of understanding to sell 500,000 tonnes per annum of polyhalite, a grade of potash, to Sichuan Agricultural Means Group, a major agricultural production company based in the Peoples Republic of China.
3bn tonnes of polyhalite, which is processed to make premium potash fertiliser, below the protected coastline.
1951) The paragenesis of sylvine, carnallite, polyhalite and keiserite in Eskdale borings nos.
Confident: Chris Fraser, Sirius CEO and managing director PETER REIMANN SIRIUS Minerals says it's "confident" it will reach its first polyhalite up to six months earlier than planned - as shares in the mine company took a 2.
Associated Mining Construction UK will conclude the entire shaft construction at the mine site for Sirius Minerals' proposed polyhalite mine near Whitby.
The company's Ochoa project would mine potassium-rich polyhalite and process the ore to produce SOP using a unique, low-cost method dating back to research conducted in the 1920s by the U.