chrysoberyl

Chrysoberyl is a mineral species with the chemical formula BeAl2O4. It belongs to the oxide minerals and forms prismatic crystals in the orthorhombic system. Chrysoberyl occurs in metamorphic and igneous rocks, most commonly in pegmatites and schists, often associated with beryl, quartz, and feldspars. The name derives from Greek chryso- “gold” and barys “heavy,” referring to the stone’s color and high density.

Gemstone chrysoberyl is prized for its hardness and brilliance. It has a Mohs hardness of 8.5 and a relatively high refractive index, contributing to strong luster. The common color range is yellow to olive-green; colorless specimens occur, and faint pleochroism can be observed. The most famous variety is alexandrite, which exhibits a dramatic color change from greenish in daylight to reddish or purplish-red under incandescent light, due to chromium substituting for aluminum in the crystal lattice. Alexandrite-type stones were first discovered in the Ural Mountains and remain a classic source, with additional finds in Brazil, Sri Lanka, Madagascar, Tanzania, and China.

A second notable variety is cat’s-eye chrysoberyl, which displays a chatoyant, narrow band of light when cut as a cabochon. Chrysoberyl is used in jewelry for its durability and distinctive optical effects. Synthetic chrysoberyl has been produced for gemstone purposes and research, underscoring the mineral’s appeal and versatility.