Hope you don't mind if I put my 2 cents in. I would drop the supplement completely (inorganic mineral) and look to foods high in calcium, particularly the dark green leafy veggies. Alfalfa "contains calcium, magnesium, phosphorus, potassium, plus all known vitamins. The minerals are in a balanced form, which promotes absorption." (from one of my health books). I think you could find an organic powdered form in capsules.
I can give you a list of foods high in calcium if you need or want it.