Argentina
Eartern Pampean Region
Sierra de San Luís
Virorco pegmatites

SEM image courtesy of MA Galliski and J Cempírek (see Galliski et al., 2012)

Occurrence:

Rossmanite was found in the Virorco dumortierite-bearing pegmatite dikes in the Eastern Pampean Ranges of central Argentina (Galliski et al, 2012). It generally consists of sub-millimeter portions of rossmanite crystals in contact with schorl or elbaite. There is evidence of fluid exchange between the host rock and the pegmatite dikes that caused the primary elbaite-rossmanite to be partially replaced by iron-rich tourmaline. Some crystals contain multiple species of tourmaline such as rossmanite, schorl and dravite.

Typical Composition:

([]_0.51Na_0.44Ca_0.05) (Al_1.78Mn_0.29Li_0.78Fe_0.12Zn_0.02) Al₆ (BO₃)₃ [Si_5.44Al_0.54O₁₈] [(OH)_3.0 F_0.04] [(OH)_0.96F_0.04)]

X-site occupancy

Galliski MÁ, Mírquez-Zavalía MF, Lira R, Cempírek J, Škoda R (2012) Mineralogy and orgin of the dumortierite-bearing pegmatites of Virorco, San Luis, Argentina. Canadian Mineralogist 50, 873-894.

Revised 15-Oct-2013