It's pretty much standard procedure to use an absorbent material such as clay granules to deal with any kind of liquid leakage. People don't know what is leaking -- could be some nasty stuff or could be pretty safe -- but in either case the best thing to do is contain the leakage and sop it up while they're figuring out if it's just a mess to clean up or a real problem that requires more action. Palm oil is pretty safe, obviously, but it could cause a bad slip and fall accident. So that's my guess about what your dark particles are. 
