title: Cancrinite from nepheline syenite (mariupolite) of the Oktiabrski massif, SE Ukraine, and its growth history.
abstract: Secondary cancrinite, (Na5.88K<0.01)∑5.88(Ca0.62 Fe0.01Mn0.01Zn<0.01 Mg<0.01)∑0.64[Si6.44Al 5.56O24](CO3)0.67(OH)0.26(F<0.01,Cl<0.01)·2.04H2O), was found as accessory component of mariupolite (albite-aegirine nepheline syenite) from the Oktiabrski massif in the Donbass (SE Ukraine). It probably crystallized from a subsolidus reaction involving nepheline (and sodalite?) and calcite dissolved in the aqueous-carbonic fluid at the maximum temperature of 930 °C, decreasing to hydrothermal conditions. It is depleted in sodium, calcium and carbon, what results in the occurrence of vacant positions at both cationic and anionic sites. Ca-deficient cancrinite crystallized from the same hydrothermal Si-undersaturated fluids enriched in the ions such as Na(+), Ca(2+), Cl(-), F(-), HCO3(-), which formed calcite, sodalite, natrolite and fluorite. It has dark-red CL colours with patchy zoning, what indicates the variable/diverse fluid composition during its formation. In the CL spectrum of cancrinite only one broad emission band at 410 nm is observed, which can be attributed to O* center (the recombination of a free electron with an O(-) hole center). The formation of secondary CO3-rich species, i.e. cancrinite and calcite in mariupolite suggests that redox conditions in the Oktiabrski massif were oxidizing at the postmagmatic stage.
authors.affiliation: Department of Mineralogy, Petrography and Geochemistry, Faculty of Geology, Geophysics and Environmental Protection, AGH - University of Science and Technology, Kraków 30-059, Mickiewicza 30, Poland. Electronic address: dumanska@uci.agh.edu.pl.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Dumańska-Słowik
authors.affiliation: Department of Mineralogy, Petrography and Geochemistry, Faculty of Geology, Geophysics and Environmental Protection, AGH - University of Science and Technology, Kraków 30-059, Mickiewicza 30, Poland.
authors.forename: Adam
authors.initials: A
authors.lastname: Pieczka
authors.affiliation: Department of Mineralogy, Petrography and Geochemistry, Faculty of Geology, Geophysics and Environmental Protection, AGH - University of Science and Technology, Kraków 30-059, Mickiewicza 30, Poland.
authors.forename: Wiesław
authors.initials: W
authors.lastname: Heflik
authors.affiliation: Polish Geological Institute-National Research Institute, 4 Rakowiecka St., 00-975 Warsaw, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Sikorska
keywords: Alkaline; Ca-deficient cancrinite; Hydrothermal fluids; Secondary origin; Subsolidus