Sources of the Gold Quartz Veins ~ Prospecting for Gold
The veins of quartz seaming the hills in the vicinity of the richest placers, also served to point to that rock as the original source of the gold. At Carson Hill, in what was then Mariposa county, quartz had been found immensely rich; but the expense of blasting the rock out and crushing it was such, that no serious attempts were made, until 1851.