Resumo

OSTROOUMOV, Mikhail. Some mineralogical and geochemical considerations about the amazonite from the State of Chihuahua, Mexico. Rev. mex. cienc. geol [online]. 2012, vol.29, n.1, pp.221-232. ISSN 2007-2902.

This work characterizes the distinctive features that influence the geological setting of amazonite, as well as the relationship between their deposits and specific genetic types of granitoids. Mineralogical and geochemical conditions of the amazonite formation as well as the typomorphic attributes are described. New information about finding and geochemical features of the Mexican amazonite is here presented (deposit Hills Bahues, Coronado municipality). There is a chemical evolution of the amazonite from granites to pegmatites, characterized by increasing amounts of K₂O, Rb₂O, Cs₂O, PbO, Sr, U y Th, and by decreasing amounts of Al₂O₃, Na₂O, Fe₂O₃ and Ba. The amazonite characterized by a high degree of Al/Si order. All the parameters obtained from X-ray diffraction (Δ > 0.90) and infrared reflection spectroscopy show that the studied amazonite belong to the maximum ordered microcline. The colorimetric parameters of the Mexican amazonite are: λ=495-503 nm, P=10-12%, Y=34.7-35.3%. The typomorphic features and color for different amazonite generations from Hills Bahues deposit are close to the amazonites from subalcaline granitoids (Transbaikal, Siberia, Russia). The crystal chemical and spectrometric parameters of amazonite may be important for the exploration of diverse deposits of rare metals (Ta, Nb, Sn) and REE mineralizations and their economic evaluation.

Palavras-chave : amazonite; typomorphic features; Mexico.

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