Gypsum is a calcium sulfate and is formed when lakes and seas evaporate and leave deposits. Prior to being known as Furniture City, Grand Rapids' first industry was gypsum mining. This specimen includes two pieces and comes from the mines in Wyoming and Grand Rapids, Michigan.
Formula: CaSO4 · 2H2O
Calcium sulfate dihydrate
3 in." h 6 in." w ; 4 1/2" h 4 1/2" w