AMMONITE FOSSIL AGE FULL

When freshly quarried, these colors are not especially dramatic the material requires polishing and possibly other treatments in order to reveal the colors' full potential. Reds and greens are the most commonly seen colors, owing to the greater fragility of the finer layers responsible for the blues. The thicker the layers, the more reds and greens are produced the thinner the layers, the more blues and violets predominate. The iridescence is due to the microstructure of the aragonite: unlike most other gems, whose colors come from light absorption, the iridescent color of ammolite comes from interference with the light that rebounds from stacked layers of thin platelets that make up the aragonite. Under ultraviolet light, ammolite may fluoresce a mustard yellow.Īn iridescent opal-like play of color is shown in fine specimens, mostly in shades of green and red all the spectral colors are possible, however. The refractive index of Canadian material (as measured via sodium light, 589.3 nm) is as follows: α 1.522 β 1.672–1.673 γ 1.676–1.679 biaxial negative. Its hardness is 3.5–4.5, and its specific gravity is 2.60–2.85. The shell itself may contain a number of trace elements, including: aluminium barium chromium copper iron magnesium manganese strontium titanium and vanadium.

The chemical composition of ammolite is variable, and aside from aragonite may include calcite, silica, pyrite, or other minerals. They went on to form Ammolite Minerals Ltd. Marcel Charbonneau and his business partner Mike Berisoff were the first to create commercial doublets of the gem in 1967. The latter is a trade name given to the gemstone by the Alberta-based mining company Korite. Īmmolite is also known as aapoak ( Kainah for 'small, crawling stone'), gem ammonite, calcentine, and Korite. It was designated the official gemstone of the City of Lethbridge, Alberta in 2007. 1 In 1981, ammolite was given official gemstone status by the World Jewellery Confederation (CIBJO), the same year commercial mining of ammolite began. It is one of few biogenic gemstones others include amber and pearl. It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same mineral contained in nacre, with a microstructure inherited from the shell. Usually 1.52 - 1.68 (varies with mineral content) Īmmolite is an opal-like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of North America. Usually about 2.70 (varies with mineral content) Gray to brown, can be radiant blue, with primarily red to green iridescence. Unprocessed sample of ammolite a 'dragon skin' pattern is apparentĬaCO 3 aragonite polymorph, with minor amounts of calcite, pyrite, silica, and other impurities

Ammonite fossil age