Sunstone was not common until recently. Previously the best-known locality being Tvedestrand, near Arendal, in south Norway, where masses of the sunstone occur embedded in a vein of quartz running through gneiss. Due to the discovery of large deposits in Oregon, Sunstone is now readily available with new sources being found and widespread through the USA. Sunstone is a plagioclase feldspar.
It has a mohls hardness of 6-7 and a refractive index of 1.525–1.58