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Ammolite is an opal-like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of North America. It is commonly unearthed by natural erosion or through the process of various mining practices, within the perimeter of an ancient sea bed called the Western Interior Seaway . [ 2 ]
These include Placenticeras meeki, Placenticeras intercalare, Hoploscaphites, and Sphenodiscus, the baculite Baculites compressus and the bivalve Inoceramus, some of which are mined south-central Alberta to produce the organic gemstone ammolite. [3] Other fossils found in this formation include many types of shellfish, bony fish, sharks, rays ...
Ammolite is a very rare and valuable opal-like organic gemstone found only along the eastern slopes of the Rocky Mountains of the United States and Canada.It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same organic mineral that makes up nacreous pearls.
A variety of ammonite forms, from Ernst Haeckel's 1904 Kunstformen der Natur.. This list of ammonites is a comprehensive listing of genera that are included in the subclass †Ammonoidea, excluding purely vernacular terms.
Placenticeras sp. ammolite, Bearpaw Formation. At the Royal Tyrrell Museum of Palaeontology. Placenticeras has a very involute shell with slightly convex sides and a very narrow venter. Side are smooth or with faint sinuous ribs. Early whorls have umbilical tubercles that in later whorls appear higher on the sides.
Actinolite. Nephrite (var.); Adamite; Aegirine; Afghanite; Agrellite; Algodonite; Alunite; Amblygonite; Analcime; Anatase; Andalusite. Chiastolite; Andesine ...
One feature found in shells of the modern Nautilus is the variation in the shape and size of the shell according to the sex of the animal, the shell of the male being slightly smaller and wider than that of the female.
The juvenile shell, found at the apex, is coiled in one or two whorls and described as minute, about 1 centimetre (0.39 in) in diameter. Adult Baculites ranged in size from about 7 centimetres (2.8 in) ( Baculites larsoni ) up to 2 metres (6.6 ft) in length.