Material produced at the Upham East Gypsum Quarry that is not suitable to produce wallboard is typically a result of impurities being present such as clay, silt and or anhydrite. Chemically, gypsum (CaSO4•2H2O) is simply the hydrated calcium sulphate mineral form of anhydrite (CaSO4). Over hundreds of years gypsum has been hydrated (exposed to water)while anhydrite has not been exposed to the same water and remains in the “anhydrite” form. Physical characteristics of anhydrite vary slightly from gypsum in that it is harder and denser and is therefore not suitable for wallboard production. These calcium Sulphate minerals are used globally in many products including soil amendments, toothpastes, pharmaceuticals and others..
What are the actual elements included under the label “low-grade gypsum”? Is this mixture of top-level material toxic?