Petite river rock molcajete, with natural exterior.
Piedra del Río Molcajetes
High in the mountains of Oaxaca, there is one family that makes molcajetes out of natural river rock. After selecting suitable raw stones in the steep river valley below their house and workshop, they transport them by hand in woven baskets. In the workshop, the rocks are cut to have a flat base, hollowed out to have a bowl-like inner recess, then textured with hammer and chisel.
The granitic rock that this molcajete is made from is much harder than the volcanic stone more commonly used to make molcajetes. This results in a tool that wears relatively slowly, and has a satisfying heft. Salsas can also be stored or served in this molcajete, as it does not absorb liquids, unlike most other molcajetes made from volcanic rock.
This molcajete requires relatively little seasoning. Before making your first salsa, it is best to season it lightly by passing the tejolote around the bowl for a few minutes. Seasoning by grinding a bit of raw white rice is also a common technique. The rice forms a white powder, in which flakes of stone are easy to detect.
Should the interior of the molcajete and the end of the tejolote become smooth with prolonged use, a more aggressive texture can be re-established with a cold chisel and hammer. Personally, I prefer relatively smooth, worn-in molcajetes, but other folks insist that their molcajetes have more bite, to quickly process tomato skins and the like.