Aragonite is known for its varied crystal shapes; the crystals sometimes grow as hexagons or will grow with the “church steeple” effect. Some call them sputniks in reference to the similarity in looks to the Russian spacecraft of that name. The color can be white or colorless or with usually subdued shades of red, yellow, orange, brown, green and even blue, although rust oranges are the most common.
Aragonite is also the formation that is found in most sea shells. The pearlization and iridescent colors in the 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.