Andalusite
Last updated: April 2026
Strong trichroism (green, red-brown, yellow-orange) is the primary diagnostic; color variation is often visible without instruments. The chiastolite variety contains a black cross-shaped pattern of carbonaceous inclusions.
Andalusite has a specific gravity of 3.17 and a refractive index of 1.629–1.649, with a Mohs hardness of 7.0–7.5. It is biaxial −.
Physical & Optical Properties
Key Differentiators
- Striking trichroism: green / red-brown / yellow-orange, often visible to naked eye
- Chiastolite variety shows diagnostic black cross-shaped inclusions
- RI 1.629–1.649 — distinguishable from tourmaline (1.624–1.644)
- Biaxial negative; SG 3.13–3.21
Price Context
Price context is approximate. Loupewise is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying an andalusite? Loupewise walks through these tests in order — RI, SG, fluorescence, and more.
Try Loupewise Free →Studying for the GIA, FGA, or FEEG practical? Andalusite is one of the 130 species in Loupewise’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
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