I decided that I wanted to get one, and to try my hand at preparing salsa the old-fashioned way. Every Sunday there is a "tianguis" (outdoor market) held on the street just around the corner from my apartment.
This removes any dirt in the pores of the stone, and it is then washed. The "molcajete" is now sitting on the kitchen counter of my apartment. When the cleaning lady comes tomorrow, she will probably think that this crazy "gringo" is trying to go native.