GEMMOLOGICAL CHARACTERISTICS OF SENGILIT — A NEW KIND OF JEWELRY-ORNAMENTAL RAW MATERIALS OF THE ULYANOVSK REGION

Abstract

Sengilite is a trade mark of florogenic jewelry and ornamental material being mined around the village Sengilei of the Ulyanovsk region. The sangilite is a lithofected marine plant remains cemented in marl. The sangilite mainly consists of calcite (from 86 to 94 wt. %). The following minerals have been established (wt. %): pyrite 2,5—6, quartz 2, montmorillonite 3, dolomite 2, in minor quantities illite, kaolinite, jarosite, gypsum, chalcopyrite can be presented. Among the elements-admixture, Sr is presented up to 0,053 wt. % and Ba up to 0,023 wt. %. The content of radioactive and carcinogenic elements is at the background level. The original structure of plant remains is inherited in sengilite. The differently colored zones of sengilite are determined by the size and structural features of the calcite crystals, as well as the amount of pyrite inclusions, and the presence of marl. In the calcite, the following elements-admixture, (wt. %) are noted: Mg from 0,68 to 1,29, Fe from 0,14 to 0,52, insignificant amounts of Mn. According to its technological and decorative characteristics, sengilite is a new high-quality jewelry and ornamental material that allows to produce a wide range of jewelry and souvenirs. Collection and processing of sengilit in the Ulyanovsk region along with ammonites and other types of jewelry and ornamental raw materials will increase the profitability of the deposit and the range of products.