| Guide to Gypsum and Gypsum Products |
Gypsum or calcium sulfate dehydrate (Ca2So4 .2H2O) is one of the most common minerals utilized in everyday effects such as blackboard chalks, plaster of Paris, fertilizers, plasterboards and drywalls. The wallboard industry is the main consumer of gypsum.
Gypsum is available in many countries across the globe, but the major producers are Australia, Bahamas, Canada and Mexico. Gypsum crystals can grow up to 11 meters in length.
Common varieties of natural gypsum
Gypsum is a white or colorless crystal in its pure form. However, impurities can change its color to pink, tan, brown, gray, yellow, reddish brown, or blue. Strata of gypsum are found in lakes and sea water, volcanic veins, and hot springs. Typically, gypsum is of the following varieties:
White alabaster: Alabaster is a white, fine-grained variety of the mineral gypsum. It is used as an ornamental stone for creating ecclesiastical statuettes and figurines. Some forms of treated alabaster are available as plaster of Paris, marmo di Castellina, alabaster coral.
Black alabaster: As rare as it is, black alabaster is found in only three veins in the world – Italy, China and USA (Oklahoma).
Satin spar: This is the fibrous, prismatic, glassy, translucent and silky variety of gypsum that looks pearly or sometimes exhibits some coloration. Typically, satin spar occurs in seams and is attached to a base rock. Satin spar often exhibits the cat's eye effect (chatoyancy) and fluorescence.
Desert rose: Typically occurring in dry climates, desert roses are flower-like gypsum deposits that get embedded with sand grains. They are opaque, soft, and bladed and have an exterior druse. Impurities such as copper, iron, coal, calcite, sulfides can color the crystals green, brown, orange, beige, yellow, light red, etc.
Gypsum flower: This rosette shaped, opaque, and brittle crystal has fibers spreading out and can have a needle-shaped, scaly, radial, or biconvex structure.
Synthetic gypsum
Gypsum is also produced as a by-product of industrial processes such as sulfite oxidation and pyrite oxidation. Synthetic gypsum is produced during the flue-gas desulfurization process. It can be used as a raw material in the production of wallboards instead of natural gypsum and is gradually gaining popularity.
Uses of Gypsum
Gypsum is a widely used mineral. Common uses are:
Scrap gypsum derived from drywalls is being recycled in several areas in North America. Manufacturers, distributors and end-users need to be educated about the correct disposal of drywall waste for the process to become a standard. Recycled drywall can be used to make new drywall, along with recycled paper, thereby making the process energy efficient and environment friendly.
