Mineralogy of interior jewellery ammonites of the Samara region

Background. Ammonite products are increasingly gaining in popularity. Ammonites characterised by a variety of colour shades, shapes and sizes, making them suitable for manufacturing wide range souvenir jewellery products. Russia enjoys significant resources ammonites interior jewellery-ornamental quality; however, these materials remain insufficiently studied from the mineralogical point view. This article presents mineral composition gemological characteristics Upper Jurassic Samara region first time. Aim. To describe stratigraphic position region. Materials methods . Late (45 samples) were collected number their main locations. The characteristic types interior-jewellery quality distinguished studied. Experiments included determination microhardness (25 determinations), density (12 luminescence features (10 samples), optical petrographic analysis (5 thin sections), as well quantitative chemical (3 electron probe studies (2 samples). Results characterized presence mother-of-pearl layer with multi-coloured iridescence. under study consist mainly apatite (21—70 wt. %) calcite (21—87 along quartz, aluminosilicates, gypsum, pyrite, zeolites, goethite, ilmenite organic matter. chambers ammonite shells made phosphorite calcite. walls partitions have completely lost original aragonite pyrite inclusions. increased content Sr (up to 0.17 Ba 0.01 recorded trace elements ammonites. Calcite contains following (wt. %): Mg — 0.17, Mn Fe 1.14, 0.11, Y 0.17. Conclusion (including microinclusions elements) was established commercial interest samples. Their shell fragments can be used production. coastal cliffs beach area Volga river, thereby requiring no capital investments producing environmental pollution.