Gypsum comes in several colors, including white, yellow, brown, red, gray, clear and colorless and, according to Geology.com, has white streaks. It is an evaporite mineral---a soft rock that can be scratched with your fingernail. Its chemical notation is CaSO4.2H20, and gypsum is used in several applications, including wallboard, plaster of Paris and as a hardening retarder in Portland cement. Although some varieties of gypsum such as satin spar and alabaster are used for ornamental purposes, these varieties have a lower hardiness, thus limiting durability.
Gypsum is an ingredient in Portland cement, used for creating cement footers for landscaping with bricks, blocks or pavers. If you have sandy soil, incorporate a 94-pound bag of Portland cement into a 30-square-foot area with a rototiller, then tamp it down and water lightly. This creates a footer used as a base for patios and walkways.
Gypsum is used for soil conditioning because of the benefits in soil containing high sodium content. It reclaims saline areas and slick spots, is implemented to soften alkali hard pans and is used to infuse calcium into the soil. If the irrigation in your landscaping has a lot of calcium and magnesium, it is not recommended that you use gypsum to amend the soil. It can be applied at a rate of 1 to 10 tons per acre, depending on the results of a salt-alkali soil test. According to the North Central Regional Extension Publication 95, if you use less than 500 pounds per acre, gypsum does not completely condition the soil, but only works as a sulfur or calcium source.
Gypsum could be used in its natural rock form to create edging in the landscaping, or it can be used in its "dried" form---plaster of Paris---to create statues, flower pots and other ornamentals for landscaping. When gypsum is heated, the two molecules of water in gypsum's chemical makeup evaporate, leaving a dry powder form of the mineral. This dry powder is known as plaster of Paris. Adding water to the dried form creates a material that can be molded into various objects used in landscaping, then dried and painted.