Galuskinite, Ca7(SiO4)3(CO3), a new skarn mineral from the Birkhin gabbro massif, Eastern Siberia, Russia.

SIBERIA, Eastern (Russia); RUSSIA

In addition to spurrite, Ca5(SiO4)2(CO3), and tilleyite, Ca5(Si2O7)(CO3)2, galuskinite, Ca7(SiO4)3(CO3), is the third mineral in the CaO–SiO2–CO2ternary system. Galuskinite, monoclinic, space group P21/c(a= 18.79, b= 6.72, c= 10.47 Å, β = 90.79°, V= 1322 Å3, Z= 4), occurs in thin veins which cut calcio-olivine, γ-Ca2SiO4, skarn with larnite, β-Ca2SiO4, relics. Pavlovskyite, Ca8(SiO4)2(Si3O10), and dellaite, Ca6(Si2O7)(SiO4)(OH)2, form a margin between the veins and the calcio-olivine skarn. The sanidinite facies high-temperature skarn formed ∼500 Ma ago when gabbroid rocks of the Birkhin complex (Baikal area, Eastern Siberia, Russia) intruded and contact-metamorphosed limestone xenoliths. Galuskinite is a retrograde product of skarn alteration and has neither been described from cement clinker production processes nor from studies of the CaO–SiO2–CO2system. The crystal structure of galuskinite, refined from single crystal X-ray data to R1= 3.1%, has a modular character. One may define a polysomatic series with spurrite and larnite as endmembers and galuskinite as a 1:1 polysome built from regular alternating spurrite and larnite modules. Differences between the X-ray powder patterns of galuskinite and spurrite are most obvious in the low y region. Galuskinite is named after the Russian mineralogists Irina O. Galuskina and Evgeny V. Galuskin, Faculty of Earth Sciences, University of Silesia, Poland, for their outstanding contributions to skarn mineralogy. [ABSTRACT FROM AUTHOR]

Copyright of Mineralogical Magazine is the property of Cambridge University Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)