I cannot be specific but it would be tiny in a 15ml dose - not more than 10-20mg - so you are fine to add other supplements to your diet if you feel the need to.
Microbz is a live fermented brew with a foundation of effective micro-organisms and then added herbs and minerals. These benefit both the microbes and us in small quantities, to feed the microbes and to nudge our bodies, through the signature of the ingredients which the microbes pick up, to re-balance and absorb nutrients more effectively. We then need to ingest more nutrients through our diets, though a really healthy biome also makes nutrients for us. So it is a different angle to specific mineral and vitamin supplements which aim instead to replace what is lacking in the diet and absorption and which are lab tested for exact amounts. The exact quantity varies between microbz batches.