is KAl(SO4)2 12H2O hygroscopic, deliquescent, or efflorescent?

Answer 1

http://chemistry.about.com/od/growingcrystals/ig/Crystal-Photo-Gallery/Alum-Crystal.htm

Those crystals are very stable in air.

However, the unhydrated crystal, KAl(SO4)2 is a powdery compound that is hygroscopic in air, and crystallizes to form one of the hydrated crystals.

Answer 2

How i am observed it