biaxial crystall

physics

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 17, 2026

Quick Summary

Biaxial crystals are a type of crystal that has or relates to two axes, specifically optic axes. In optical crystallography, crystals are classified by their interaction with polarized light. Biaxial crystals are distinct from optically isotropic crystals (which have one refractive index) and optically uniaxial crystals (which have two refractive indices).12

Biaxial crystals exhibit three principal refractive indices, with one index along each of the three mutually perpendicular optical axes. These optical axes can correspond to the crystallographic axes in systems like the orthorhombic system, or have a less fixed relationship in systems such as the monoclinic and triclinic systems.2

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

optical crystallography
Optically biaxial crystals (all of which exhibit three principal refractive indices, one along each of the mutually perpendicular optical axes) in which the three optical axes correspond to the three crystallographic axes (orthorhombic system);
Read More
Optically biaxial crystals (all of which exhibit three principal refractive indices, one along each of the mutually perpendicular optical axes) in which the three optical axes correspond to the three crystallographic axes (orthorhombic system);
Read More