Serpentinite

Serpentinite is safe to handle except in powder form. If you plan to cut or polish serpentinite, it's advisable to wear a dust mask to avoid inhaling any dust. Asbestos fibers are hazardous when inhaled, as they can lead to serious lung disease.

Serpentinite exhibits poor toughness due to its serpentine-rich composition, characterized by a platy structure prone to separation and breakage, rendering it unsuitable for high-impact daily use.

Serpentinite's susceptibility to water, direct sunlight, heat damage, and chemical reactions makes it less ideal for daily use where such exposures are common.

Serpentinite can form from olivine via several reactions. Olivine is a solid solution of forsterite, the magnesium-endmember, and fayalite, the iron-endmember.

Serpentinite is easily carved, making it an excellent rock for creating small artifacts, trinkets, and gemstones. Serpentinite is also a major source of asbestos, a once popular material for building insulation, paint filler, and other construction materials that has fallen out of use due to its linkage with lung cancer.

Serpentinization is a geological low-temperature metamorphic process involving heat and water in which low-silica mafic and ultramafic rocks are oxidized (anaerobic oxidation of Fe by the protons of water leading to the formation of H2) and hydrolyzed with water into serpentinite. Peridotite, including dunite, at and near the seafloor and in mountain belts is converted to serpentine, brucite, magnetite, and other minerals — some rare, such as awaruite (Ni3Fe), and even native iron. In the process large amounts of water are absorbed into the rock increasing the volume, reducing the density and destroying the structure. The density changes from 3.3 to 2.7 g/cm with a concurrent volume increase on the order of 30-40%. The reaction is highly exothermic and rock temperatures can be raised by about 260 °C (500 °F), providing an energy source for formation of non-volcanic hydrothermal vents. The magnetite-forming chemical reactions produce hydrogen gas under anaerobic conditions prevailing deep in the mantle, far from the Earth's atmosphere. Carbonates and sulfates are subsequently reduced by hydrogen and form methane and hydrogen sulfide. The hydrogen, methane, and hydrogen sulfide provide energy sources for deep sea chemotroph microorganisms.