They include carnallite, cuprite, dolomite, gypsum, halite, hematite, magnesite, pyrite, quartz, rectorite, rinneite, sylvite and syngenite
It was obtained that the best conditions of reaction for the production of potassium sulphate are: temperature of reaction 5[grados]C; the crucial factor in the system studied is the effect of the ammonia which both promotoes the formation of potassium sulphate and also hinders its conversion to syngenite
, the initial solvent composition 32% by weight ammonia in water; weight ratio of gypsum to solvent of 1:5 and size of 75 smaller grain of mehs.
Most of the unusual species described below, including anhydrite, boracite, ericaite, hilgardite, magnesite, rectorite and syngenite
were identified by X-ray powder diffraction at Manchester University.