Found in a late-stage breccia pipe that cuts the Zapot amazonitic microcline - topaz - zinnwaldite granitic pegmatite.
Approved IMA 1998 (Dana # Added)
Gillis Range, Mineral County, Nevada, U.S.A. Link to MinDat.org Location Data.
Named after William B. "Skip" Simmons (b. 1943), University of New Orleans, New Orleans, Louisiana, U.S.A., specialist in the mineralogy and petrology of granitic pegmatites, especi ally those of Colorado and of NYF type