Ammolite
Ammolite, also called Korite or Calcentine, is a rare and beautiful opal-like treasure that is organic. It’s one associated with the three biogenic gemstones, the other two Amber that will be and. Ammolite is a fossilised shell that is ammonite. Ammonites were the sea that is squid-like that lived about 71 million years ago. Ammonites inhabited a prehistoric, inland sea that is subtropical bordered the Rocky Mountains in the western United States and Canada. This sea is famous today because the Cretaceous or Interior that is Western Seaway. As this sea receded, the Ammonites had been crushed and hidden by layers of bentonite sediment. This sediment preserved the shells comprising Aragonite, preventing them from converting to Calcite. Most fossilised shells from other locations worldwide have had their pseudomorphous that is aragonite replace Calcite or Pyrite making the existence of Aragonite in Ammonite shells particularly rare. Ammonites became extinct along with dinosaurs at the final end of the Mesozoic era.
The exterior layer of the shell that is ammonite of Aragonite and it is what’s used to make Ammolite gems. This layer is usually very thin, up to 1 mm dense, and delicate. Ammolite gems are generally fabricated into triplets with quartz or synthetic spinel top layers and a backing that is shale. Quartz is a top that is good Moh’s hardness of 7 but is notably brittle. Synthetic Spinel is a better top with Moh’s hardness of 8 and it is more durable.
Fine samples of Ammolite are prized for their breathtaking, iridescent, opal-like play of colour. This selection of colours can be acquired mostly in shades of reds and greens although all the colours that are spectral possible. The iridescence in Ammolite is a result of the microstructure of the Aragonite. Along with on most gems comes from light refraction. The iridescent colours of Ammolite come from interference using the light that rebounds from stacked layers of thin platelets. Thicker layers produce more reds and greens and thinner levels produce more blues and violets. Reds and greens are the more colours being common blues and violets being rarer.
Ammolite is available from several sources across the Rocky Mountains. However, significant deposits of gem-quality Ammolite are observed in the Bearpaw development that extends from Alberta to Saskatchewan in Canada and south to Montana in the United states. Probably the grade that is best of treasure quality Ammolite is found regarding the eastern slopes of the Rockies in southern Alberta. Most mining that is commercial of is along the banks associated with Lehigh River in an area between the towns and cities of Summit Hill and Lethbridge.
| Category: | Fossilized, Mineralized Ammonite Shell |
| Chemical Formula: | CaCO3 aragonite polymorph, with minor amounts of calcite, pyrite, silica, and other impurities. |
| Cleavage: | No true cleavage |
| Fracture: | Uneven to granular |
| Specific gravity: | Usually about 2.70 |
| Tenacity: | Very Brittle (until fabricated into triplets topped with Quartz or synthetic Spinel) |
| Moh’s Hardness: | raw material: 2.80; Quartz topped triple: 7.0; Syn. Spinel topped triplet: 8.0 |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Full spectrum of colors possible; iridescent/opalescent |
| Transparency: | Opaque |
| Lustre: | Vitreous to Resinous |
| Refractive Index: | 1.52 – 1.68 |
| Optical properties: | Anomalous aggregate reaction |
| Birefringence: | 0.135 – 0.145 |
| Pleochroism: | None |
