Moonstone with Black Tourmaline

Physical Properties

Hardness: 6.0-6.5 (Mohs scale), Color: Opalescent white/colorless with black inclusions, Luster: Vitreous to pearly, Crystal Structure: Monoclinic, Cleavage: Perfect in two directions

Formation & Geological History

Formed in plutonic igneous rocks (magmatic) and pegmatites. The moonstone effect (adularescence) is caused by the intergrowth of two types of feldspar that separate as the magma cools.

Uses & Applications

Predominantly used in jewelry (cabochons), ornamental carvings, and by mineral collectors. It is also a popular stone in metaphysical circles.

Geological Facts

The shimmering effect, known as adularescence, is caused by light scattering between microscopic layers of orthoclase and albite. The black spots are inclusions of Schorl, the most common type of Tourmaline.

Field Identification & Locations

Identify in the field by its distinct pearly sheen and the presence of needle-like or blocky black inclusions. Commonly found in Sri Lanka, India, and Madagascar.

Identified on: 4/18/2026

Mode: Standard