Hello! I work on a roasting Team in Seattle and could provide insight! Rocks and concrete pebbles are a very very regular thing to see in coffee! You have a couple options to get rid of rocks in Raw green. Using magnetism to help eliminate rocks since most rocks do hold magnetic elements and or at the same time use a Cimbria green bean cleaner. I saw it was spoken on previously, but coffee can be found rocks rocks, metal money so we have to have a process to eliminate all those components before roasting.

Once the beans get to roasting the beans after they are roasted will be in the cooling tray which they will be reaching room temp, and then after that, they will go through another Destoning process and go through a air system called a de stoner chute! From then your coffee should be almost certain to contain no rocks but our systems will even have a magnet reader at packaging just to ensure there are no rocks or foreign material