... , Pure gypsum is transparent or colorless, with fibrous, needle-like, flake an Dihydrate gypsum’ chemical formula is CaSO4•2H2O, ... Pure gypsum is transparent or colorless, with fibrous, needle-like, flake and other crystal forms. Natural gypsum mines often ... contain more impurities from the production-like look, with transparent plaster, fiber plaster, alabaster, flake gypsum, clay earth ...