Aluminum-magnesium variety of caryopilite from goethite-neotocite-rhodochrosite ores of the Mazulskoe manganese deposit (Krasnoyarsk region)

A. I. Brusnitsyn, E. V. Belogub, N. V. Platonova, V. V. Shilovskikh, I. G. Zhukov.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2018. V. 147. N 6. P. 90-103

https://doi.org/10.30695/zrmo/2018.1476.04

Full text is available on eLIBRARY.RU

Language: Russian

Abstract

Results of the investigation of caryopilite from goethite-neotocite-rhodochrosite ore of the Mazul manganese deposit, Krasnoyarsk Krai, Siberia, Russia. Caryopilite forms lamellar crystals; optical properties of mineral are following: Ng — yellow, Np — pale yellow, n_m 1.60, n_g – n_p 0.010—0.015. Chemical composition of the studied ñaryopilite corresponds to the empirical formula (Mn_1.95Mg_1.61Al_0.58□_0.23)_5.00[(Si_3.88Al_0.12)_4.00O₁₀](OH)₆, where □ is vacancies. Concentration of Mg, unusually high for caryopilite, and high content of admixed Al allow to distinguish a new aluminium-magnesium variety of this mineral. It is formed under low temperatures as a result of the rep lacement of a primary, sedimentary neotocite. It is assumed that at temperature increase Al-Mg-rich caryopilite loses magnesium and aluminium which further concentrate in magnesian-manganese chlorite and spessartine.

Key words: caryopilite, neotocite, Mazulskoe manganese deposit, Krasnoyarsk Region.