PIAGET. 
Fig. 1. A recrystallized mica — quartz schist. The dark, parallel stripes are biotite, 
the large grains quartz. Nic. +. Magn. 28 X. Cerro Potrero Viejo. Quebrada 
Agua de los Caballos. 
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Fig. 2. Sericitic, microfolded ferriferous schist. Nic. +. Magn. 20 X. Sierra de 
Umango ridge, eastern side. Quebrada Salto (N from Casa Piedra). 
