It looks brittle but will get the job done with proper use. Slightly touching each other while rapidly rotating won’t cause self breakage but will break the commodity in between instead.
Grinding machines and stones are not created equal. Expensive machines are well built, easier to adjust, and have longer service life. Affordable grinders are affordable for several reasons. Discover them for yourselves.
Inspect the stone thoroughly for damaged and cracks. Scrape off any excess powdery sand. Never use a damaged or cracked stone. Wash thoroughly in several changes of lukewarm water. Then rinse with hot water.
Stone absorbs water including the juices, color and flavor of commodity being ground. So a pair of grinding stone should be used only on a single commodity. Another pair is needed for the other. If budget permits, acquire a separate grinding machine for the other product.
Place over several layers of clean towel immediately after washing. Towel with absorb water fast thereby reducing the drying time. Avoid storage while the stone is still wet. Moist will encourage microbial growth resulting to bad odor and possible product contamination.
For storage. Cushion the pair of stone with towel or thick paper and place in a tightly sealed container. Keep away from dirt and odorous substances.
Stones wears and may break thru use. Always keep a spare or two in case replacement is necessary.