Aragonite

Aragonite has poor toughness due to its brittleness and natural cleavage planes, making it prone to breaking easily during daily use.

Aragonite's susceptibility to water solubility, heat-induced transformation, difficulty in stain removal, and chemical reactivity make it sensitive for daily use.

Aragonite is thermodynamically unstable at standard temperature and pressure, and tends to alter to calcite on scales of 10 to 10 years. The mineral vaterite, also known as μ-CaCO3, is another phase of calcium carbonate that is metastable at ambient conditions typical of Earth's surface, and decomposes even more readily than aragonite.

The type location for aragonite is Molina de Aragón in the Province of Guadalajara in Castilla-La Mancha, Spain, for which it was named in 1797. Aragonite is found in this locality as cyclic twins inside gypsum and marls of the Keuper facies of Triassic. This type of aragonite deposit is very common in Spain, and there are also some in France and Morocco. An aragonite cave, the Ochtinská Aragonite Cave, is situated in Slovakia. In the US, aragonite in the form of stalactites and "cave flowers" (anthodite) is known from Carlsbad Caverns and other caves. Massive deposits of oolitic aragonite sand are found on the seabed in the Bahamas. Aragonite is the high pressure polymorph of calcium carbonate. As such, it occurs in high pressure metamorphic rocks such as those formed at subduction zones. Aragonite forms naturally in almost all mollusk shells, and as the calcareous endoskeleton of warm- and cold-water corals (Scleractinia). Several serpulids have aragonitic tubes. Because the mineral deposition in mollusk shells is strongly biologically controlled, some crystal forms are distinctively different from those of inorganic aragonite. In some mollusks, the entire shell is aragonite; in others, aragonite forms only discrete parts of a bimineralic shell (aragonite plus calcite). The nacreous layer of the aragonite fossil shells of some extinct ammonites forms an iridescent material called ammolite. Aragonite also forms in the ocean and in caves as inorganic precipitates called marine cements and speleothems, respectively. Aragonite is not uncommon in serpentinites where high Mg in pore solutions apparently inhibits calcite growth and promotes aragonite precipitation. Aragonite is metastable at the low pressures near the Earth's surface and is thus commonly replaced by calcite in fossils. Aragonite older than the Carboniferous is essentially unknown. It can also be synthesized by adding a calcium chloride solution to a sodium carbonate solution at temperatures above 60 °C (140 °F) or in water-ethanol mixtures at ambient temperatures.

Currently, there are no practical uses for aragonite. However, it is a constituent of limestone which is used in the production of cement and steel. Furthermore, one study has shown that aragonite may successfully remove pollutants such as zinc, cobalt, and lead from water.

Aragonite is an energizing stone that is believed to improve self-confidence and promote self-discipline. It is an excellent stone for anyone learning patience and tolerance. Its positive energy stimulates motivation and puts a stop to procrastination. This not only allows the person to move forward in their life goals but also discourages feelings of anger and stress. Often used in meditation, its potent energies align and activate all of the chakras.