Magnesite

The poor toughness of magnesite is attributed to its perfect cleavage, allowing for easy splitting along specific planes. This structural flaw increases its susceptibility to chipping and breaking under stress.

Magnesite's susceptibility to water, heat, stains, and chemicals indicates that it requires careful handling and is not ideal for daily use where such exposures are common.

Magnesite can be formed via talc carbonate metasomatism of peridotite and other ultramafic rocks. Magnesite is formed via carbonation of olivine in the presence of water and carbon dioxide at elevated temperatures and high pressures typical of the greenschist facies. Magnesite can also be formed via the carbonation of magnesium serpentine (lizardite) via the following reaction: 2 Mg3Si2O5(OH)4 + 3 CO2 → Mg3Si4O10(OH)2 + 3 MgCO3 + 3 H2O However, when performing this reaction in the laboratory, the trihydrated form of magnesium carbonate (nesquehonite) will form at room temperature. This very observation led to the postulation of a "dehydration barrier" being involved in the low-temperature formation of anhydrous magnesium carbonate. Laboratory experiments with formamide, a liquid resembling water, have shown how no such dehydration barrier can be involved. The fundamental difficulty to nucleate anhydrous magnesium carbonate remains when using this non-aqueous solution. Not cation dehydration, but rather the spatial configuration of carbonate anions creates the barrier in the low-temperature nucleation of magnesite. Magnesite precipitation needs high pH and absence of other cations. Magnesite has been found in modern sediments, caves and soils. Its low-temperature (around 40 °C [104 °F]) formation is known to require alternations between precipitation and dissolution intervals. Magnesite was detected in meteorite ALH84001 and on planet Mars itself. Magnesite was identified on Mars using infra-red spectroscopy from satellite orbit. Near Jezero Crater, Mg-carbonates have been detected and reported to have formed in lacustrine environment prevailing there. Controversy still exists over the temperature of formation of these carbonates. Low-temperature formation has been suggested for the magnesite from the Mars-derived ALH84001 meteorite. The low-temperature formation of magnesite might well be of significance toward large-scale carbon sequestration. Magnesium-rich olivine (forsterite) favors production of magnesite from peridotite. Iron-rich olivine (fayalite) favors production of magnetite-magnesite-silica compositions. Magnesite can also be formed by way of metasomatism in skarn deposits, in dolomitic limestones, associated with wollastonite, periclase, and talc. Resistant to high temperature and able to withstand high pressure, magnesite has been proposed to be one of the major carbonate bearing phase in Earth's mantle and possible carriers for deep carbon reservoirs. For similar reason, it is found in metamorphosed peridotite rocks in Central Alps, Switzerland and high pressure eclogitic rocks from Tianshan, China. Magnesite can also precipitate in lakes in presence of bacteria either as hydrous Mg-carbonates or magnesite.

Magnesite is burned to make magnesium oxide, a refractory material used in various industrial furnaces. It is also used in the making of some flooring materials, synthetic rubber, as well as magnesium chemicals and fertilizers. Magnesite is also used for creating ornamental stones and jewelry. Being porous, it is often cut, drilled, and dyed in a broad spectrum of colors.

Magnesite is a powerful stone that aids the Crown and Third Eye chakras to encourage creativity and deeper meditation. It is often used to aid one in psychic visions and manifestation. When used on the Heart chakra its positive energy encourages self-love and improves self-esteem and confidence. It aligns the chakras for better health of the mind, body, and spirit.