Assertion: halite | /r/HasAspect | impurities of gypsum
Facets:
Source sentences:
text: It can have impurities of gypsum (CaSO4) and sylvite (KCl) but it is very rare to find potassium sulfate as a mineral, although occasionally polyhalite (K2Ca2Mg(SO4)4.2H2O) is found associated with rock salt deposits.