How big is the rock?

Using it as a blower would let you blow it off the rocks to where you can sweep it up and put it back.

Hmm, good point. It's mainly 3/4" to 1 1/2".

Shouldn't be a problem if the area is small enough to use an electric leaf blower/vacuum combination unit AND the mulch doesn't contain large pieces of wood. Most have at least two speeds so it can be cranked down to pick up the light stuff without catching large wood pieces or stone. We've used a base-level Craftsman unit (May not work if the mulch includes small branches or large chips of wood or bark because they could jam the suction fan, but any small or soft stuff should be fine.