![]() ![]() ^ "Chapter 186–State Emblems State Boundary 2017".Archived from the original on 24 April 2015. ![]() Oregon Department of Geology and Mineral Industries. ^ "Rock Hounding: Oregon Sunstone-Official State Gemstone".and Rossman G.R., 1985, Exsolution of metallic copper from Lake County labradorite: Geology, v.13, p. "Gem News International: Visit to andesine mines in Tibet and Inner Mongolia Gemological properties of andesine collected in Tibet and Inner Mongolia". ^ Abduriyim, Ahmadjan Kobayashi, Taisuke (2008)."The characteristics of red andesine from the Himalaya Highland, Tibet". "A Mine Trip to Tibet and Inner Mongolia: Gemological Study of Andesine Feldspar" (PDF). ^ Abduriyim, Ahmadjan (10 September 2009).^ "Three Occurrences of Oregon Sunstone - Gems & Gemology".Utah Geological Survey, accessed September 14, 2007. ^ Sunstones at Sunstone Knoll, Millard County.On August 4, 1987, the Oregon State Legislature designated Oregon Sunstone as its state gemstone by joint resolution. The copper leads to variant color within some stones, where turning one stone will result in manifold hues: the more copper within the stone, the darker the complexion. Oregon Sunstone is unique in that crystals can be quite large. Oregon Sunstone contains elemental copper. Oregon sunstone Ī variety known as "Oregon sunstone" is found in Harney County, Oregon and in eastern Lake County north of Plush. A Tibetan source of bona fide (untreated) red andesine, however, was eventually verified by a number of independent groups of well-respected gemologists. After much controversy and debate, most of these gemstones, allegedly sourced from China, were subsequently discovered to have been artificially colored by a copper diffusion process. In the early 2000s, a new variety of red or green gemstone resembling sunstone and known as "Andesine" appeared in the gem market. Other locations include near Lake Baikal in Siberia, and several United States localities-notably at Middletown Township, Delaware County, Pennsylvania Plush, Oregon and Statesville, North Carolina. 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. The feldspar which usually displays the aventurine appearance is oligoclase, though the effect is sometimes seen in orthoclase: hence two kinds of sunstone are distinguished as "oligoclase sunstone" and "orthoclase sunstone". The middle part of this crystal sparkles, and usually the color is darkest in the middle and becomes lighter toward the outer edges. The optical effect is called schiller and the color of Oregon Sunstone is due to copper. These inclusions give the stone an appearance something like that of aventurine, hence sunstone is known also as "aventurine-feldspar". The optical effect is due to reflections from inclusions of red copper, hematite, or goethite, in the form of minute scales, which are hexagonal, rhombic, or irregular in shape, and are disposed parallel to the principal cleavage-plane.
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