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Andalusite By Doug Miller
The andalusite occurrences have very easy access for collectors, being immediately on the south side of the Hanson Lake Road from 101 to 103 km east of the intersection of Highway 165 (from La Ronge) with the Hanson Lake Road. A variety of andalusite called chiastolite may also be occasionally found at these sites. Chiastolite is a highly impure cigar-shaped crystal that forms with distinctive cross-like inclusions. Polished cross sections of chiastolite are distinctive and attractive. Andalusite is brittle but tough, has a hardness of 7.5 (3.5 to 4.5 for chiastolite), and conchoidal fracture. Specific gravity is 3.1 to 3.2. Index of refraction is approximately 1.64. Andalusite is slightly birefringent (0.007 to 0.011). Pleochroism visible without a dichroscope sets andalusite apart from most gems. Brazilian material appears green through the prism faces and deep brownish-red through the c axes.
Permission is given to freely reprint this article from the Canadian Rockhound for non-commercial and educational purposes, provided the author and the Canadian Rockhound are acknowledged, and that the website URL address of the Canadian Rockhound is given. The article may not be edited or rewritten to change its meaning or substance without the author's permission. To contact the author, please use the e-mail address provided. Courtesy copies of newsletters using this article are requested for the author. The preceding article was first published in the November 1997 issue of the Saskatoon Lapidary & Mineral Club newsletter. Reprinted in the Canadian Rockhound with permission from the author.
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