Sodalite
Last updated: April 2026
Opaque to translucent blue sodium aluminum silicate chloride; chemically distinct from lapis lazuli (a rock containing lazurite, calcite, and pyrite). Strong orange LW fluorescence and low SG (~2.27 vs lapis ~2.75) are the primary field separations. Hackmanite is a pink/colorless variety showing tenebrescence (reversible color change under UV). Typically lacks the gold pyrite flecks present in lapis lazuli.
Physical & Optical Properties
RI Range1.483–1.487
SG Range2.14–2.40
SG Typical2.27
Hardness (Mohs)5.5–6
Crystal SystemCubic
Optic CharacterAggregate
Dispersion0.000
Fluorescence LWInert
Fluorescence SWInert
Chelsea FilterInert
PleochroismNone
ColorsBlue Violet, Colorless
SpeciesSodalite
Related: Sodalite Varieties
Key Differentiators
- Hackmanite variety shows strong orange LW fluorescence (tenebrescence); plain sodalite is inert to LW UV — lapis lazuli shows only weak orange LW
- Very low SG (~2.27) — lapis lazuli averages ~2.75
- No pyrite inclusions — lapis almost always has gold pyrite flecks
- Uniform blue — no calcite matrix or lazurite patches
Common Simulants
- Lapis Lazuli: Lapis: SG ~2.75 (much heavier); weak orange LW fluorescence (vs sodalite's strong orange); pyrite inclusions characteristic; aggregate RI spot ~1.50–1.67 range. Lapis is a rock, sodalite is a mineral.
- Blue Glass: Glass: isotropic; conchoidal fracture; gas bubbles under magnification; SG varies; no fluorescence match.
Commonly Confused With
Commonly confused with: Lapis Lazuli.
Treatments
- Waxing / impregnation — surface stabilization (common for opaque stones)
Price Context
Natural — low ($/ct)$2
Natural — high ($/ct)$25
NotePer carat; common ornamental stone; deep royal blue with minimal white veining most valued; Greenland/Namibia material highest quality
Price context is approximate. GemID is not an appraisal tool. Results are indicators, not certified valuations.
Measurement Guides
Identifying a sodalite? GemID walks through these tests in order — RI, SG, fluorescence, and more.
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