Provincial Symbols of Alberta - Ammolite (Paperback)

Chapters: Ammolite. Source: Wikipedia. Pages: 67. Not illustrated. Free updates online. Purchase includes a free trial membership in the publisher's book club where you can select from more than a million books without charge. Excerpt: Ammolite is a rare and valuable opal-like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of the United States and Canada. It is arguably the rarest gemstone on earth, rivaling the rarity of such gemstones as alexandrite and red diamonds. It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same mineral that makes up nacreous pearls. It is one of several biogenic gemstones; others include amber and pearl. In 1981, ammolite was given official gemstone status by the World Jewellery Confederation, the same year commercial mining of ammolite began. It was designated the official gemstone of the Province of Alberta in 2004 and the official gemstone of the City of Lethbridge in 2007. Ammolite is also known as aapoak (Kainah for "small, crawling stone"), gem ammonite, calcentine, and korite. The latter is a trade name given to the gemstone by the Alberta-based mining company Korite International, the first and largest commercial producer of ammolite. The chemical composition of ammolite is variable, and aside from aragonite may include calcite, silica, pyrite, or other minerals. The shell itself may contain a number of trace elements, including: aluminium; barium; chromium; copper; iron; magnesium; manganese; strontium; titanium; and vanadium. Its crystallography is orthorhombic. Its hardness is 4.55.5, quite soft for a gemstone, and its specific gravity is 2.602.85. The refractive index of Canadian material (as measured via sodium light, 589.3 nm) is as follows: 1.522; 1.6721.673; 1.6761.679; biaxial negative. Under ultraviolet light, ammolite may fluoresce a mustard yellow. An iridescent opal-like play of color i...More: http: //booksllc.net/?id=1702572