- Bytownite
Bytownite is a calcium rich member of the
plagioclase solid solution series offeldspar mineral s. It is usually defined as having "%An" between 70 and 90. Like others of the series, bytownite forms grey to whitetriclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations.The
specific gravity for bytownite varies between 2.74 and 2.75. The refractive indices ranges are nα=1.563 - 1.572, nβ=1.568 - 1.578, and nγ=1.573 - 1.583. Precise determination of these two properties with chemical,X-ray diffraction , or petrographic (birefringence andoptic angle ) analysis are required for identification.Bytownite occurs in
gabbro intrusion s and in metamorphic complexes. The mineral was first described in 1835 and named for an occurrence at Bytown (nowOttawa ),Canada .References
* Hurlbut, Cornelius S.; Klein, Cornelis, 1985, "Manual of Mineralogy", 20th ed., Wiley, ISBN 0-471-80580-7
* [http://www.mindat.org/min-815.html Mindat with locations]
* [http://mineral.galleries.com/minerals/silicate/bytownit/bytownit.htm Mineral galleries]
* [http://webmineral.com/data/Bytownite.shtml Webmineral data]
Wikimedia Foundation. 2010.