Sunstone
Sunstone is an iridescent variety of plagioclase feldspar containing tiny oriented platelets of copper or hematite that produce a metallic sparkle (aventurescence). Oregon and Norway are the classic sources.
About Sunstoneextended article
Plagioclase feldspar with copper inclusions producing aventurescent flash.
Full mineralogical data
Sunstone is a named variety, not a separate species. For complete data on chemistry, crystal system, hardness, optics, paragenesis, treatments, and inclusions — refer to the parent species:
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About Sunstone
Sunstone is a member of the plagioclase feldspar series, ranging from oligoclase to labradorite in composition. The defining aventurescent flash comes from micron-scale platelets of native copper (Oregon material) or hematite/goethite (Norwegian material) suspended in the host crystal. These reflectors are oriented along specific crystallographic planes and produce the characteristic shimmer when light strikes the right angle.
Identification & care
Sunstone has a Mohs hardness of 6 to 6.5 and a specific gravity around 2.62 to 2.65. Cleavage is good in two directions at near-right angles, fracture conchoidal to uneven, luster vitreous to pearly. The diagnostic feature is the aventurescent flash, visible as glints of red, gold, or green within an otherwise transparent to translucent host crystal. Oregon copper sunstone often shows a continuous red color in addition to the flash.
Collector context
Collector notes
Oregon sunstone from the Ponderosa and Spectrum mines is the most prized variety, with collector grade material showing strong red-to-green color shifts and visible copper schiller. The Norwegian (Tvedestrand) hematite-included material is the historic source described in early mineralogy texts. Indian sunstone is more abundant, less expensive, and usually shows weaker aventurescence. Sunstone is a cabinet- to thumbnail-scale collectible — large transparent terminated crystals are rare.