Most bivalve animals and corals secrete aragonite for their shells and pearls are composed of mostly aragonite. The pearlization and iridescent colors in sea shells such as abalone are made possible by several minute layers of aragonite. Other environments of formation include hot springs deposits, cavities in volcanic rocks, caves and mines. Color can be white or colorless or with usually subdued shades of red, yellow, orange, brown, green and even blue. Luster is vitreous to dull.
Crystals are transparent to translucent.
Can also be compact, granular, radially fibrous and massive. Its massive forms can be layered, coralloid, pisolitic, oolitic, globular, stalachtitic and encrusting. Aragonite is a constituent of many species' shell structures. A layered sedimentary marble like formation is called Mexican Onyx and is used for carvings and ornamental purposes. Calcite pseudomorphs of aragonite crystals and formations are common.