No better evidence can be found of the extensive operations which have been carried on in this the greatest mining district of Northern Mexico, than in the little mountains of scoria [dregs] which are found in the suburbs of the city. A great number of poor laborers make a regular business of hammering to pieces these metallic excrescences, from which they collect silver enough to buy their daily bread.

Commerce of the Prairies (1831–1839), Chapter 22 - Visit to Town of Jesus-Maria — Anti-Masonic Auto de Fe