What is Vesuvianite?
Vesuvianite, also known as idocrase, is a calcium-rich silicate found in contact-metamorphic rocks and valued as both a collector mineral and a gemstone.
Mineralogy and structure
Reference formula: Ca10Mg2Al4(SiO4)5(Si2O7)2(OH)4. Vesuvianite is tetragonal with a complex framework and broad chemical substitutions. Idocrase is a historical synonym, not a second page. The COD 1011221 ferrian vesuvianite model is labelled representative. Vesuvianite is classified with silicates and has tetragonal crystal symmetry. Typical hardness is 6.5–7 on the Mohs scale and specific gravity is approximately 3.3–3.5.
Colour, lustre and habit
Typical colours include green, brown, yellow, white, blue-green, violet. The usual prismatic, massive, granular habit and vitreous, resinous lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Vesuvianite forms in or is associated with skarns, metamorphosed limestones, marble contacts and calcium-rich hydrothermal systems. Important documented localities include Quebec in Canada, Italy, California, Pakistan, Russia, Tanzania and Afghanistan.
The idocrase gemstone with a skarn origin
Vesuvianite combines gem potential with serious geological context. Bright green, blue-green or cinnamon material becomes more desirable when transparency, polish, crystal form and classic locality are documented.
Collecting and care
Protect from sharp impact and acids. Clean with mild water and a soft brush; retain locality and treatment information for faceted or polished material.
