Only as mineral specimens Specimens Hanksite is an unusual mineral mostly because of its formula. It is one of only a handful of minerals that contain both carbonate and sulfate ion groups.
Some mineral references place it in the carbonates while others put it in with the sulfates.
We have placed it in the sulfate class simply because there are more sulfate groups in its structure than carbonate groups. Hanksite forms very nice crystals in evaporite deposits. These evaporite deposits occur in arid environments. Water, carrying dissolved minerals, floods into a dry lake beds and then just sits. The arid conditions evaporate the water and concentrate the ions.