On the front? near the pulley? Probably belt dust. Check your belt alignment and it's surviving width, and the integrity of the alternator mounts and the waterpump front bearing. Also slip the belt off and check that all the pulleys freewheels smoothly.
If it is belt dust, this is a big deal. If the belt fails and you don't catch it, you are well on your way to engine overheat. And if you don't catch that either then you are only minutes away from making a loan to replace the engine. Or at least the heads.
