In the region about Acton are many hills of liparite (quartz-bearing
trachyte) and tufa, which are identical with the rhyolites of the Calico
region—the same violet-brown, porphyritic liparite; the same pea-green
and buff-colored tufas; the same conglomerate; in fact, an exact
facsimile of the Calico range. There are no great beds of sedimentary
rock, however, and these liparite hills are comparatively small,
isolated masses. As far as my knowledge goes ores of silver have never
been found in these rocks in the Acton district. Careful prospecting may
possibly discover such ores.