Deep core mining is the current credit meta with Elite: Dangerous 3.3. How it works is you look around asteroid belts using a new utility module called a Pulse Wave Scanner, and the previously existing prospector limpets, to find asteroids with a juicy gem core. Once you find one, you can crack it open using a seismic charge launcher to get at the valuable resources inside.
The hard part about this is the "finding" part, though. How can I identify asteroids that may have a deep core that I can crack open? Obviously this can be done slowly by firing a prospector at every glowing rock, but is there any way to identify these rocks before firing a prospector?