Gypsum Varieties

Selenite

• Selenite describes the transparent form of gypsum, though it may also have a tinge of white or other colors to it. Selenite frequently has a glassy, silky appearance and sometimes appears as though it can break off into narrow, needle-like slivers. On the cleavages, the luster becomes pearly, giving it the characteristic "white" outer edges. This mineral can be found all over the world, particularly in the Salt Plains of northern Oklahoma. Many people often mistake selenite for calcite, but selenite is softer and does not react with acid.

Satin Spar

• Satin spar gets its name from the very satin-like luster characteristic of this type of gypsum. When first discovered, scientists believed it to be of the spar family, giving it the second part of its name. Satin spar is primarily found in central North America, from Indiana to California and as far south as Arkansas and Arizona. It's also found in southern Australia. This type of gypsum often is used in jewelry making, because of its cat's eye-like luster, coming from the fibrous nature of the mineral.

Alabaster

• This fine-grained gypsum enjoys popularity in the artistic community as a carving medium. Its colors range from shades of whites, to reds, yellows and browns. Occasionally, it may exhibit color bands. Since it can also be dyed, alabaster sometimes is used as a substitute for and sold as other gemstones, notably jade. It is a highly dense stone displaying luster ranging from pearly to slightly glassy or soapy in appearance. Some specimens may be slightly translucent. Alabaster is often referred to as "gypsum rock" and can be found in places such as Tuscany, Italy and Derbyshire, England.

Desert Rose

• When most people hear the word "gypsum," they think of the Desert Rose variety. This specimen occurs in rosettes, or flower-like formations. They generally range from an off-white to a brown color, because of sand occlusions. This type of gypsum is prevalent in many desert areas that are also rich in brine, or salt, from the sea. This brine crystallizes to form a Desert Rose, and it can grow up to a meter. Desert Rose is sometimes also called Desert Flower, but many geologists like to point out that Desert Flowers more commonly occur in desert caverns than under the sand, and often are white, because of a higher selenite composition.