Sunstone
Image: James St. John (CC BY 2.0)
Mineral NameSunstone
Chemical Formula(Na,Ca)(Al,Si)AlSi2O8
Mohs Hardness6
Crystal Systemtriclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect in two directions, nearly at 90 degrees
Fractureuneven
Specific Gravity2.65
Colorsyellowish-greenish, colorless, yellow, orange, red, pink, green
Transparencytransparent
Type LocalitySpectrum Mine, Oregon, USA
Mineral GroupSilicates
Usesjewelry, collector
Associated Mineralsnative copper, pyroxene, olivine
Rarityuncommon
Description
A faceted, oval-shaped sunstone gemstone, approximately 1.3 cm across, displaying a yellowish-greenish body color and internal schiller from copper inclusions. It is transparent.
Geological Context
Sunstone forms as plagioclase phenocrysts within Tertiary-aged, porphyritic, mafic volcanic rocks, with its characteristic aventurescence caused by tiny native copper inclusions.
