"Before dark they encountered laboring up the western slope of the mountain a conducta of one hundred and twenty-two mules bearing flasks of quicksilver for the mines."
Quicksilver being transported from New Almaden mine (1850)
Creative Commons AttributionQuicksilver being transported from New Almaden mine (1850) - Credit: Rice Digital Scholarship Archive

Quicksilver is an archaic name for mercury, a necessary element for refining silver from ore.

It is likely McCarthy is referring to quicksilver from the New Almaden mine in San Francisco when he describes the conducta as being ‘twenty-six days from the sea’ (p.204). According to Bartlett, ‘there was but one other mine in the world, that of Almaden in Spain, where the operation [of quicksilver refining] was carried out on a large scale’.

Jesús María, the conducta’s intended destination, was one of Mexico’s great silver-mining areas.