Grossular
Image: James St. John (CC BY 2.0)
Mineral NameGrossular
Chemical FormulaCa3Al2(SiO4)3
Mohs Hardness7
Crystal Systemcubic
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity3.65
Colorsred, light tan, olive-green, olive-brown, colorless, yellow, orange, pink
Transparencytransparent
Type LocalityMexico
Mineral GroupSilicates
Usesjewelry, collector, abrasives
Associated Mineralsquartz, feldspar, diopside, calcite, vesuvianite
Rarityuncommon
Description
The image displays several well-formed grossular garnet crystals, ranging in color from red and light tan to olive-green and olive-brown, with sizes between 1.4 and 2.6 centimeters across. These crystals exhibit a characteristic vitreous luster and distinct isometric forms.
Geological Context
Grossular typically forms in contact metamorphic rocks, particularly in calc-silicate skarns, marbles, and serpentinites, often resulting from the metamorphism of impure limestones or dolomites.
