Zeolite mineral forming distinctive coffin-shaped tabular crystals. Common in basalt cavities worldwide. Color: White, pink, red, orange. Luster: Vitreous to pearly. Streak: White. Cleavage: Perfect in one direction. Hardness: 3.5-4. Transparency: Transparent to translucent. Crystal system: Monoclinic. Chemical formula: Ca,Na ₅ Si₂₇Al₉ O₇₂·26H₂O. Specific gravity: 2.1-2.2. Formation: Forms in cavities in basaltic lavas from circulating hydrothermal fluids at temperatures below 200°C. Common geological settings: India, Iceland, Italy, USA; found in vesicles of basaltic lavas. Common look-alikes and related entries: Stilbite, Chabazite, Apophyllite.
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These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
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GeoMiner
Last updated
2026-03-30T14:37:47.953979+00:00
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Published; not independently peer-reviewed
IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
Zeolite mineral forming distinctive coffin-shaped tabular crystals. Common in basalt cavities worldwide.
How can you identify Heulandite?
Compare several properties rather than relying on colour alone. This entry records colour: White, pink, red, orange; lustre: Vitreous to pearly; streak: White; Mohs hardness: 3.5-4; cleavage: Perfect in one direction; crystal system: Monoclinic; transparency: Transparent to translucent. Confirm an important identification with additional field tests or qualified laboratory work.
How does Heulandite form?
Forms in cavities in basaltic lavas from circulating hydrothermal fluids at temperatures below 200°C.
Where is Heulandite commonly found?
India, Iceland, Italy, USA; found in vesicles of basaltic lavas.
What is Heulandite commonly confused with?
Heulandite may be confused with Stilbite, Chabazite, Apophyllite. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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