This is a molcajete, the traditional mortar and pestle tool of Mexico and Central America.  They've also been found at archaeological sites in the Southwest.  These have been used since ancient times for making salsa and grinding spices.  It is made of hard, porous volcanic rock.  My boyfriend's mom gave this to me.  It belonged to her grandmother and is around 100 years old.  If taken care of they can last for many generations and improve with age.  I love possessions like this.  The molcajete gives a texture to salsas that is far superior to the blender and also makes a beautiful bowl for presentation.  I only recently tried grinding spices in it.   (I didn't for a long time because I was afraid the flavor would linger.  It didn't though.)  Toasted cumin seeds for chili or cardamom pods for chai tea grind up easily and quickly from the rough surface (much faster than the common ceramic mortar and pestles.)  Grinding food between two stones is also just really fun- though I'm sure my boyfriend's great gradmother would have been grateful for the blender.

cardmom pods for chai tea grind up easily