Worm Gold Plus Worm Castings by Boogie Brew, the only Castings that have rock mineral dust added. Check them out.
From their site,
"Our worms and their castings are also supplemented with extra soil super-chargers in the form of biodynamic humus soluble kelp extract (the kelp we add is fossilized kelp), along with collodial rock dust. This produces a truly superior casting, which will positively charge your soil with new life and give plants a mega-dose of beneficial biology. The potent quantities of beneficial microbes produced by the worms’ digestion help the elements in soil work together to create a healthy substrate and an optimum growing environment. By improving soil structure, Worm Gold Plus promotes better root zone oxygenation. Worm Gold Plus also provides a gentle blend of nutrition which plants can then feed on as needed for weeks on end. High quality castings are a great source of nitrogen, phosphorous, potassium, calcium, magnesium, plus more than 50 trace minerals and micro-nutrients."