Cassiterite
Last updated: April 2026
A tin oxide mineral that is the most important ore of tin, rarely seen as a gemstone.
Cassiterite has a specific gravity of 6.95 and a refractive index of 2.010–2.100, with a Mohs hardness of 6.0–7.0. It is uniaxial +.
Physical & Optical Properties
RI Range2.010–2.100
SG Range6.80–7.10
SG Typical6.95
Hardness (Mohs)6–7
Crystal SystemTetragonal
Optic CharacterDR Uniaxial (+)
Birefringence0.096
Dispersion0.071
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismStrong Dichroic
ColorsBrown, Black, Yellow Orange
SpeciesCassiterite
Key Differentiators
- Extremely high specific gravity
- High RI and birefringence
- Adamantine luster
Treatments
- Surface-Scratched False Asterism (fraud)
Price Context
Natural — low ($/ct)$30
Natural — high ($/ct)$200
NotePer carat; rare collector gem; adamantine luster; brown to yellow
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a cassiterite? GemID walks through these tests in order — RI, SG, fluorescence, and more.
Try GemID Free →Studying for the GIA, FGA, or FEEG practical? Cassiterite is one of the 130 species in GemID’s drill and exam pool — practice identifying it from its measured properties under timed exam conditions.
Practice exams →