From GeologyCafe.com
The small mines were dug to gather barite and travertine ore that was processed for paint (whitewash) for the Mexican communities in the region.
Did you slide around on the marble up top?
That marble is old seafloor metamorphosed by igneous intrusions and uplifted by the mighty San Andreas.
The same marble (part of the Sur Series) is exposed on the UCSC campus.
