Calcium sulfate is a calcium salt which occurs abundantly in the natural environment and also appears as a byproduct of some industrial processes. The chemical formula for this material is CaSO4, and it comes in two primary forms: an anhydrous form and a hydrous form. The different forms have a wide range of applications, ranging from making casts for treatment of fractured limbs to creating works of art.

In nature, calcium sulfate is a clear white rock. It is often sold in the form of a powder, which may be mixed with an indicator dye which stains the powder when it is exposed to water. It can also be sold in blocks, which are typically rough and unfinished as people will be modifying the block for an intended use. In nature, calcium sulfate is quarried from a number of sites around the world. This calcium salt is also produced to meet specific needs, and recycled when it occurs as a byproduct of manufacturing.

The hydrous form is sometimes known as alabaster or gypsum. Historically, it has been used to create sculptures and other works of art. It can also be heated and ground to create plaster of Paris, a powder which can be mixed with powder and cast into a hard form. Plaster of Paris is used in the arts, in medical practice, and in the construction of models of all shapes and sizes. Many craft stores stock plaster of Paris for craft projects.

The anhydrous form of calcium sulfate is used as a desiccant and coagulant in a number of industrial processes. When it is used as a desiccant, it is often packaged with indicator dyes so that people are aware when moisture intrusion has occurred. As a coagulant, it shows up in some processed foods such as tofu. Anhydrous calcium sulfate is a tremendously useful product which can be seen in a wide range of applications.

Globally, production of calcium sulfate varies. Some nations lack natural deposits and may need to import it, while others have ample deposits which they can quarry and process as needed. This material is needed in a wide array of industries, and as a result, demand for calcium sulfate usually remains very steady. Companies which process this product for specific uses such as sculpture or desiccation sell both to members of the public and to dealers, with different price points available to buyers.