Specimens of picromerite in dry air will dehydrate forming the mineral langbeinite and will turn cloudy. For this reason specimens of picromerite should be stored in sealed containers. Picrmerite lends its name to a group of sulfates called the Picrmerite Group . These sulfates are all monoclinic, have medium to large sized cations and have six water molecules. The A cation can be either potassium or ammonium, NH 4 .
Color is white, colorless, reddish, gray or yellowish.
Luster is vitreous. Specimens are translucent to opaque. Crystal Habits include granular, earthy and encrusting masses. Individual short prismatic crystals are rare. Cleavage is perfect.