Safety first: wear safety glasses when pounding rocks as bits do break can fly off at great speed!

Mortar and pestles materials

Mortar and pestles can be made out of different materials:

1. Grey agate - strong
2. Glass - not strong enough for this use
3. Wood - possibly too soft and will get dented by rough surfface of the rocks
4. Ceramics - fragile
5. Porcelain - good for finer grinding and blending of pigments. Can be roughened up by grinding with ......see video.

It's important to use a mortar and pestle strong enough to handle the initial pounding of the rocks.

The video shows the use of heavy granite mortar and pestle, often used for asian-style cooking. The inner hase is smooth.