Where is Grossular Garnet found?
Grossular (Ca3Al2(SiO4)3)
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Open the appGrossular Garnet occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Grossular Garnet
Kenya and Tanzania
World-renowned for high-quality Tsavorite (green grossular) found in Neoproterozoic metamorphic rocks of the Mozambique Belt.
Canada (Quebec, British Columbia)
Known for various colors of grossular, including orange-brown Hessonite and green varieties, often in skarn deposits.
Mexico (Sierra de Cruces, Coahuila)
Produces fine orange-brown Hessonite crystals, often in skarn environments.
USA (Vermont, California, Alaska)
Vermont is known for green grossular (hydrogrossular) in serpentinites. California and Alaska have occurrences in metamorphic and skarn settings.
Italy (Val d'Ala, Piedmont)
Classic locality for well-formed grossular crystals, often in calc-silicate rocks.
Pakistan
Produces fine quality Hessonite and other grossular varieties.
Collecting tips
- Target Metamorphic and Skarn Environments. Focus your search on areas known for contact metamorphic aureoles around granitic intrusions into carbonate rocks, or regionally metamorphosed calc-silicate units. Look for outcrops with other calc-silicate minerals like diopside, wollastonite, and epidote.
- Look for Characteristic Crystal Forms. Grossular often forms distinct dodecahedral or trapezohedral crystals. Even if embedded, these forms can be discernible on weathered surfaces or in broken rock.
- Observe Color and Luster. The wide range of colors, from colorless to vibrant green or orange, combined with a vitreous to resinous luster, can help distinguish grossular from other minerals in the matrix.
- Test Hardness. With a Mohs hardness of 6.5-7.5, grossular will scratch glass and steel. This helps differentiate it from softer associated minerals.
- Check for Lack of Cleavage. Garnets do not exhibit cleavage. If you observe distinct cleavage planes, it is likely not grossular.
Quick Check
- Color:
- Variable (colorless, yellow, orange, green, brown)
- Luster:
- Vitreous to resinous
- Streak:
- White
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