Great find at the Mercado Juarez!
At the Mercado Juarez there were many molcajetes for sale. There were small & large molcajetes made of terracotta too which I have never seen in the states. These are almost certainly used for soft items like avocados. I found a very sweet little molcajete carved in the shape of a pig. There were several carved into a heart shape. This being a more traditional wedding gift for someone who likes to cook. Here in Mexico the common curing process for the basalt molcajete is to grind rice or dry beans to smooth the surface of the bowl & then wash it & grind up several cloves of garlic & then leave it to dry. When it is washed the final time it is ready to use. The garlic keeps the earthy flavor of the stone from getting into the food.
...and this Little Piggy went wee, wee, wee, all the way home! Silly & yet so appropriate!