"Polyhalite-stone - A type of non-carbonate salt that is composed of particles of the sulphate mineral polyhalite. British Geological Survey Research Report RR/99/03, section 7.1 and fig. 11."@en . "Polyhalite-stone"@en . . "stable"@en . "POYHST"@en . . . "Polyhalite-stone"@en . .