Caracterização e análise do potencial gemológico de turmalinas de Quixeramobim, Ce, Brasil

Abstract

This project has as it main aim the gemological characterization of specimens from Quixeramobim (CE) that have potential to be used as gemstones. This region belongs to the Pegmatitic District Solonópole - Quixeramobim (DPSQ), the DPSQ is inserted in the Central Ceará Domain which belongs to the Borborema Province (northern zone). Studies were carried out regarding the gemological properties, in addition to the data regarding its chemical composition; the evaluation of its gemological quality and calculation of commercial value; the analysis of these samples in the Polariscope Gomes (Constructive Arrangement Introduced in Polariscope for Gem Study and Analysis) to verify the degree of ease when viewing the interference figure; Raman spectrometry and analysis for crystallographic orientation. The specimens in blue, green and pink have the same gemological characteristics as tourmaline from other regions, although they can have some variations in some properties. Minerals have good color quality and noticeable fluid inclusions. Tourmaline has interference figures that are moderately easy to see. Thus, through the listed gemological instruments and accurate analysis, it was possible to verify an excellent commercial and optical characterization and evaluation. Noting that several gemological and chemical properties are standard for the mineral group, but characteristics such as: birefringence, pleochroism and relative density are anomalous, these irregularities are caused by the content of the iron element; the character and optical sign do not have characteristics that allow a study of provenance; the correlation between pleochroism and the interference figure is linked to the amount of sodium. So the work has a compilation of the data of these minerals in this municipality in Brazil, also proving that the specimens have good to medium characteristics to be used as gems.