Crystallomorphological and physical properties of apatite from carbonatites

Abstract

This paper presents the results of the study of x-ray luminescence of apatite from different genetic types of apatite species in order to study its geochemical characteristics and the possibility of using as a mineral indicator the conditions of ore formation and for search purposes. Apatite Ca2Ca3(F,Cl,OH)2[PO4]3 contains impurities Gd3+, Ce3+, Eu2+, Dy3+, Sm3+, Nd3+ as well as Mn2+ and others. Syngony is hexagonal. Crystals of prismatic habit; usually ending in dipyramide or basopinacoid. Sometimes forms tabular crystals. A hexagonal prism is often preserved. Color greenish, bluish-green; pinkish-purple, gray; often white, colorless or brown. Quite often translucent due to the presence of small internal cracks and inclusions; sometimes the inclusions are arranged oriented, preferably parallel to the main axis of the crystal. Brightly luminesces in cathode, x-ray and ultraviolet rays. The intensity and color of luminescence varies widely depending on the impurities. The presence of three crystal chemical positions in the structure of apatite – two cationic and one anionic makes it possible to be realized in the mineral by a wide heterovalent substitution. The distribution of isomorphic impurities between the crystal chemical positions will depend on the type of cation, its amount, as well as anionic substitutions in apatite. To determine the luminescence intensity values of the characteristic isomorphic impurities of apatite TR3+ (Gd3+, Ce3+, Eu2+, Dy3+, Sm3+, Nd3+) and Mn2+, the X-ray luminescence method was applied. Apatites of different genetic types of the Aldan, Baltic Shields, the Baikal region (Russia), the Sette-Daban Range, and the Maimech-Kotui Province (Yakutia) and the Ukrainian Shield were investigated. The obtained values of luminescence intensity of TR3+ and Mn2+ can be used to diagnose the genetic type of apatite species, the conditions of mineral formation, the type of their mineralization and for search purposes. On the basis of factor analysis, it can be concluded that the intensity of the luminescence centers of rare earth elements in the apatites of each complex depends on the relative age position of the mineral in the groups of successively formed rocks. Analysis of apatite carbonatites from different deposits showed minimal fluctuations in the ratios of radiation intensity of X-ray centers (Ce3+, Sm3+, Mn2+, Eu2+), which may indicate a close geochemical situation and, consequently, the only source of matter in the formation of carbonates. Analysis of apatite carbonatites from different fields showed minimal fluctuations in the radiation intensity ratios of the centers of X-ray luminescence (Ce3+, Sm3+, Mn2+, Eu2+), which, in my opinion, may indicate a close geochemical situation and, as a consequence, the substance or the result.