An analysis of geochemical features of crystallization of emeralds as an approach to determine the deposit of them

Abstract

Relevance. It is known that minerals differ in morphology, features of the internal structure of crystals, chemical composition, etc., depending on the conditions of their formation and existence. These geochemical features of the gems crystallization are an important criterion for determining their deposit. In this paper, the impurity composition of the samples of emeralds from the deposits of Brazil, China, Zambia, Russia, Afghanistan, Colombia, and Tanzania was investigated by X-ray fluorescent analysis. The study of the impurity composition of emeralds by a non-destructive method and the construction of analytical dependences can be used as an additional way for determining the deposit of emeralds. Purpose of the work is the study of chemical composition of emeralds by X-ray fluorescent analysis to establish the relationship between the content of the main impurity elements and the deposit. Results. The data on the impurity composition of emeralds obtained by X-ray fluorescent analysis show that the content of impurities of Na, K, Rb, Cs, Mg, Fe, V, Cr differs from one deposit to another. The content of impurities of alkali metals and magnesium is higher in the samples from the shale-type deposits compared to the samples from deposits of the Colombian type. Thus, at the first stage, the type of deposit can be assumed. Further, the dependences plotted in the coordinate planes {Cr, V}, {Cs, Cr}, {Fe, Cr} show separate areas, delimited by the impurity ratios, which are typical for the samples from deposits in China, Colombia, Zambia, Afghanistan, and Tanzania. Conclusion. X-ray fluorescent analysis, as a non-destructive method for studying emeralds, is considered to be a promising approach to identifying their deposit, but as an additional method.