{"id":18682,"date":"2024-10-18T13:05:41","date_gmt":"2024-10-18T13:05:41","guid":{"rendered":"https:\/\/www.tajan.com\/?p=18682"},"modified":"2024-11-04T11:08:49","modified_gmt":"2024-11-04T11:08:49","slug":"a-large-iridescent-ammonite-on-sale-november-20","status":"publish","type":"post","link":"https:\/\/www.tajan.com\/en\/a-large-iridescent-ammonite-on-sale-november-20\/","title":{"rendered":"A large Iridescent Ammonite on sale November 20"},"content":{"rendered":"

On sale November 20, 2024<\/h4>\n

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This exceptional specimen<\/a> features superb ammolite mineralization, precious gem recognized as such by jewelers, on both sides, one with shimmering iridescent reds, golds and greens, the other with a rainbow of blues, greens, yellows, purples, dark browns and tan. The colors change hue and intensity as they diffract light from different angles as it swings on its support, giving it multiple appearances. The piece thus becomes a fascinating work of natural art, in the world of Surrealism.<\/p>\n

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Large iridescent ammonite Placenticeras meeki<\/em><\/strong><\/p>\n

\u00a0Upper Cretaceous (approx. 73 million years ago)<\/p>\n

Bearpaw Formation, Canada, displayed on a personalized rotating stand (with metal patina).<\/p>\n

Dimensions:
\nDiameter of largest part: 48.5 cm (19,1 in) Thickness: 6.5 cm (2,56 in)
\nHeight with display stand: 69 cm (27,16 in) Width with display stand: 48.5 cm (19,1 in)<\/p>\n

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Placenticeras<\/em> was a fast-swimming carnivorous cephalopod, the taxonomic class that includes today’s octopus, nautilus and squid. Like a submarine, these ammonites used gas and fluid-filled chambers to regulate their position in the water column. The animals themselves lived only in the outermost compartment, using their tubular siphon to connect its chambers along the ventral surface of their shell.<\/p>\n

While dinosaurs ruled the earth during the Late Cretaceous, Placenticeras ammonites could be found in oceans all over the world. However, the vast majority of this species made their home in the Western Interior Seaway, an ocean that bisects North America from the Artic Circle to what is now the Gulf of Mexico. In ideal preservation conditions, a deceased ammonite would sink to the bottom of the sea and get filled with sediment. Over time, its muddy grave eventually mineralized into shale, and it is these ancient shale deposits of the Canadian Rockies that have produced the world’s largest – and only gem-quality – deposits of ammolite (a semi-precious stone recognized worldwide).<\/p>\n

Along with amber and pearl, ammolite is one of the world’s few biogenic substances. Resembling opal, it is found exclusively in ammonite shells that have undergone the fossilization process known as permineralization.<\/p>\n

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The quality of gem ammolite is determined by a number of factors, the first and most obvious being its number of primary colors – reds and greens, which are fairly common, while blues and purples hardly ever appear. Also of great importance is the amplitude of ammolite’s chromatic change, graduated by the way its colors change hue and intensity as they diffract light at different angles. Finally, the amplitude of an ammolite’s iridescence also has an impact on its quality and value, with the finest specimens displaying broad, uninterrupted bands of vibrant, rainbow colors. With all these indicators, this ammolite specimen ranks exceptionally well.<\/p>\n

As a stunning example of an ammonite from Canada’s world-renowned Bearpaw Formation, the Placenticeras meeki offered is, literally, a sheering example of one of the most beautiful ammolite fossils ever to be put on the market. It is, in the expert’s own words, an exceptionally large, iridescent ammonite with superb ammolite mineralization.<\/p>\n

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Expert: Mr Eric Mickeler, Former, Sotheby’s and Christie’s consultant in Natural History, curator of the Dinosauria Museum Prague, Czech Republic.<\/p>\n

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