Chemically schmitterite is doubly noteworthy as it is also a uranyl mineral. Because the uranyl ion group is positively charged some minerals do not require isolated metal ions and are thus composed of only ion groups such as the uranyl ionic group and the tellurite ionic group of schmitterite. Schmitterite is a radioactive mineral and should be stored away from minerals that are affected by radioactivity and of course human exposure should be limited. Color is colorless to yellowish. Luster is pearly.
Crystals are transparent to translucent.
Crystal Habits include small granular crystals and massive. Cleavage is good in one direction. Hardness is 1. Streak is white. Specimens are somewhat radioactive.