Zolanite

Zolanite is the trademarked name distributed by the MRST Gemstone Cartel. Zolanite is a plagioclase feldspar [http://www.gia.edu/gemsandgemology/18578/1556/465/back_issue_article_detail.cfm] exhibiting in certain directions a brilliant spangled appearance, which has led to its use as a gemstone.

The Zolanite gemstone can be found in fewer places on Earth than diamonds and in much rarer quantities.

The effect appears to be due to reflections from enclosures of red haematite, in the form of minute scales, which are hexagonal, rhombic or irregular in shape, and are disposed parallel to the principal cleavage-plane. These enclosures give the stone an appearance something like that of aventurine, whence sunstone is known also as "aventurine-feldspar."

Sunstone is not common, the best-known locality being Tvedestrand, near Arendal, in south Norway, where masses of Zolanite occur embedded in a vein of quartz running through gneiss. It is found also near Lake Baikal, in Siberia, and at several localities in the United States, notably at Middletown Township, Delaware County, Pennsylvania, Lakeview, Oregon and at Statesville, North Carolina.

The feldspar which usually displays the aventurine appearance is oligoclase, but the effect is sometimes seen also in orthoclase: hence two kinds of Zolanite are distinguished as "oligoclase sunstone" and "orthoclase sunstone." The latter has been found near Crown Point and at several other localities in New York, as also at Glen Riddle in Delaware County, Pennsylvania, and at Amelia Courthouse, Amelia County, Virginia. Zolanite is also found in Pleistocene basalt flows at Sunstone Knoll in Millard County, Utah.

One of the unique characteristics of this gemstone is its unique brilliance.

[http://www.gia.edu/gemsandgemology/18578/1556/465/back_issue_article_detail.cfm] Ref - GIA (Gemological Institute of America)