FEATURES OF MINING UPPER DEVONIAN MOROCCAN AMMONITES SUITABLE FOR JEWELRY AND ORNAMENTAL PURPOSES

Huge quantity of decorative Moroccan ammonites enters the world market. Of commercial interest is the Upper Devonian dense limestone layer containing great many ammonites and other fossils. The blocks 30–60 cm thick are cut by dozers and shovels, without blasting. The mineralogy of the fossilized limestone suitable for jewelry and ornamental purposes is comprehensively studied using X-ray technique and electron microprobe analysis. The rock contains 95 wt% of calcite with a small quantity of dolomite, quartz, aluminosilicate, pyrite, goethite, apatite and nondecrystallized substance, some particles contain barite. Due to high content of goethite, the rock has brown and reddish-brown color. Regarding impurity elements, stable content is recorded for Sr from 0.01 to 0.07 wt% and Ba from 0.003 to 0.02 wt% (one sample contained 6.67 wt%). Cancer-causing and radioactive elements show nearly background content.

The experience gained in mining and processing of decorative ammonite in Morocco can be useful in Russia holding considerable reserves of this unique raw material for jewelry and ornamental purposes.

Keywords

Raw material for jewelry ad ornamental purposes, fossilized limestone, goethite, cancer-causing and radioactive elements, Morocco.

Issue number: 2
Year: 2018
ISBN:
UDK: 553.5 (64)
DOI: 10.25018/0236-1493-2018-2-0-34-41
Authors: Petrochenkov D. A.

About authors: Petrochenkov D.A., Candidate of Geological and Mineralogical Sciences, Assistant Professor, e-mail: p-d-a@mail.ru, Russian State Geological Prospecting University named after Sergo Ordzhonikidzе (MGRI-RSGPU), 117997, Moscow, Russia.

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