Arrastras, simple ore-grinding mechanisms, were introduced into California by experienced Mexican miners and many were in use in Calaveras County. They were made out of local materials at little cost and were very efficient in crushing ore. A shallow pit was excavated and then lined with fitted stones on the bottom and sides. A drag stone was fitted with eyebolts from which it was dragged around a center post by human or animal energy. The pulverized stone was then washed in pans or cradles to collect the gold. When abandoned, the base stones were pulled up to retrieve gold dust that had filtered through the cracks.