Mineral Guide · Mineral

Grossular

Grossular is the calcium-aluminium garnet, occurring in a broad colour range from colourless and white to green, yellow, pink and cinnamon-brown.

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Crystal structure

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Mineral properties

Formula: Ca₃Al₂(SiO₄)₃
Class: Silicates
Crystal system: Cubic
Typical colours: green, yellow, colourless, white, pink, orange-brown
Lustre: Resinous, Vitreous
Hardness: 6.50-7.00
Specific gravity: 3.50-3.70
Crystal habit: Dodecahedral, Granular, Massive
Origin: calcium-rich skarns, contact-metamorphic marbles, serpentinites and metamorphosed impure limestones

Related varieties

What is Grossular?

Grossular is the calcium-aluminium garnet, occurring in a broad colour range from colourless and white to green, yellow, pink and cinnamon-brown.

Mineralogy and structure

Reference formula: Ca₃Al₂(SiO₄)₃. Grossular is a cubic garnet species. Tsavorite and hessonite are popular grossular varieties, while hydrogrossular represents a hydrated composition in the same range. Grossular belongs to the silicates and has a cubic crystal system. Typical hardness is 6.5–7 on the Mohs scale and specific gravity is approximately 3.5–3.7.

Colour and appearance

Typical colours include colourless, white, green, yellow, pink, orange-brown. The usual dodecahedral, granular, massive habit and vitreous, resinous lustre are useful descriptive features, but colour alone is not diagnostic.

Formation and localities

Grossular forms in or is associated with calcium-rich skarns, contact-metamorphic marbles, serpentinites and metamorphosed impure limestones. Important documented localities include Kenya, Tanzania, Canada, Mexico, Sri Lanka, Pakistan, Italy and the United States.

Collecting and care

Record the confirmed species or variety and locality; colour alone does not distinguish grossular from related garnets.

Sources and editorial review

Reviewed by NotOnlyRocks Editorial Team

Last reviewed: 31 August 2026

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