Moonstone

Hardness: 6-6.5 on Mohs scale. Color: Typically colorless to white, with adularescence exhibiting blue, white, or rainbow shimmer. Luster: Vitreous to pearly. Crystal Structure: Monoclinic; commonly massive, columnar, or tabular crystals. Cleavage: Perfect in two directions. Specific Gravity: 2.56-2.62.

Formed in igneous and metamorphic rocks, specifically in pegmatites and granitic intrusions, and also in hydrothermal veins. The characteristic adularescence is caused by the diffraction of light within microscopic lamellar intergrowths of two different feldspar types (orthoclase and albite). Geological Age: Varies depending on geological location and formation events, often associated with ancient mountain-building processes.

Predominantly used as a gemstone in jewelry due to its unique optical phenomenon (adularescence). It has been popular for centuries and is often cut en cabochon to enhance its shimmer. It is also used as a collector’s stone.

Moonstone is a feldspar mineral, belonging to the orthoclase variety. The most prized moonstones exhibit a blue shimmer. It is often associated with feminine energy and intuition. In many cultures, it is believed to be a sacred stone. It is the state gem of Florida, USA.

Identify by its characteristic adularescence (a floating play of light, often blue or white, across the surface of the gem). It is commonly found in Sri Lanka, India, Madagascar, Myanmar, Tanzania, the USA (especially in Virginia and New Mexico), and Brazil. In the field, one would look for feldspar-rich rocks. For collectors, look for strong adularescence and good transparency; 'rainbow moonstone' is a trade name for labradorite that exhibits a similar effect but is chemically different.