Тип публикации: статья из журнала
Год издания: 2021
Идентификатор DOI: 10.15506/JoG.2021.37.6.608
Аннотация: In 2017, small quantities of ammonites showing a colourful iridescent nacreous surface began to appear on the Russian market. The deposit is located near Norilsk in the former Taymyr (Dolgan-Nenets) Autonomous Okrug, Krasnoyarsk Krai, north-western Siberia. The ammonites (Placenticeras sp. nov.) are encased in calcareous sandstone Показать полностьюconcretions associated with Late Cretaceous (Turonian) sedimentary deposits, and were glacially transported from an unknown location. The nacreous surface consists of 93 wt.% aragonite with minor apatite, vaterite, calcite and siderite; traces of pyrite and quartz are also present. Iridescence of the fossilised nacreous surface is associated with preserved platy aragonite layers of the ammonite shell. The aragonite microcrystals are 1.5-2.5 mu m wide and 0.4-0.6 mu m thick, and their structure and size determine the iridescence colour. The colourful appearance of the material is enhanced by treatment (impregnation with epoxy resin), and the resulting product can be used to make a wide range of decorative products and jewellery items. (C) 2021 Gem-A (The Gemmological Association of Great Britain)
Журнал: JOURNAL OF GEMMOLOGY
Выпуск журнала: Vol. 37, Is. 6
Номера страниц: 608-617
ISSN журнала: 13554565
Место издания: LONDON
Издатель: GEMMOLOGICAL ASSOC GREAT BRITAIN