FROM THE WILUY RIVER, YAKUTIA, RUSSIA

• Main Authors: Evgeny V. Galuskin, Irina, O. Galuskina
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Si-deficient vesuvianite; hydrogarnet-type substitution; boron; wiluite; infrared spectra; Raman spectra; electron- microprobe data; unit-cell parameters; Wiluy River; Russia. SOMMAIRE; Yakutia
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.490.5633; http://rruff.info/doclib/cm/vol41/CM41_833.pdf

A low-temperature, Si-deficient variety of vesuvianite occurs in porous tetrahedral “achtarandite ” pseudomorphs consisting of hibschite, along the banks of the Wiluy River, Yakutia, Russia, the type locality of grossular and wiluite. The (H4O4)4–-for-(SiO4)4 – hydrogarnet-type substitution is evident in the vesuvianite, a substitution that allows it to be considered an analogue of hibschite. This variety of vesuvianite belongs to a new series in the vesuvianite group, as expressed by the formula X19Y13T0–5(Si2O7)4(SiO4)10–x(OH)4xW10. The filling of the X, Y, and T positions in this Si-deficient vesuvianite, where x varies from 0.67 to 2.89, is analogous to that in vesuvianite and wiluite. The Si-deficient vesuvianite is characterized by increased unit-cell parameters, a 15.688(3), c 11.860(3) Å and by lower indices of refraction, 1.691(1), 1.668(1). In the OH-region, the FTIR and Raman spectra differ sharply from those of low-temperature vesuvianite from rodingites, but are similar to the spectra of hibschite. A line near 3620 cm–1 indicates that the substitution occurs only in the isolated tetrahedra. More than 25 % of these can be substituted by (H4O4). Contents of boron up to 2.48 apfu were detected in the Si-deficient vesuvianite. The vesuvianite formed during the hydration (serpentinization and rodingitization) of early, high-temperature skarns.