Safety first: wear safety glasses when pounding rocks as bits do
break can fly off at great speed!
It's important to use a mortar and pestle strong enough to handle the initial pounding of the rocks.
Mortar and pestles can be made out of different materials:
- Grey agate - strong
- Glass - not strong enough for this use
- Wood - possibly too soft and will get dented by rough surfface of the rocks
- Ceramics - fragile
- Porcelain - good for finer grinding and blending of pigments. Can be roughened up by grinding with ......see video.
Mortar and pestles can be made out of different materials:
The video shows the use of heavy granite mortar and pestle, often used for asian-style cooking. The inner hase is smooth.