Material: natural agate (for both mortar and pestle). Hardness: 6.8-7.2. Please understand that the bottom of the agate mortar is not fine polished to improve grip friction. The amount of grinding should not exceed 1/3 of volume.
Matters needing attention:
1. do not heat or put it into the oven.
2. wash with water after use.
3. The amount of grinding should not exceed 1/3 of volume.