Fig. 12. Example of an Al-Ti-Zr projection of garnet +/- sillimanite +/- cordierite gneisses formed from igneous rocks by metasomatic fractionation form the Gold Butte area of Nevada (Fryxell et al, 1992; Collins, unpublished study). Symbols: granite gneiss = plus; garnet gneiss = open circle; garnet-sillimanite gneiss = open triangle; garnet-sillimanite-cordierite gneiss = open square. Elongate field extending across the gneisses at Gold Butte shows the trend of data points for Al-rich shale at upper right to sandstone at the lower left (Garcia et al. (1994). Figure is from Collins (in press).