(maybe vegan) Calcium Phosphate is a mineral often derived from rocks but sometimes from Whey (from cheese-making)1 and bones. It is used as a mineral supplement, an antacid, to treat various conditions including low blood calcium, in animal feeds, in fertilizers, glass making, enameling, dental products, and in the production of baking powders and wheat flour. Please check with the manufacturer to find out the source of Calcium Phosphate.
1. “Kosher Food Production” by Zushe Yosef Blech, p. 391