Hi tierra
Well I doubt you are getting enough Ca or Mg in your diet unless you are growing your own food or consuming certain superfoods like seaweeds or chlorella, the soils our foods are grown in have long been depleted and unless you know a farmer who incorporates alkaline and trace minerals in their farming practices chances are you wont be able to buy high mineral foods.
Any calcium bound with acids is good, citrate or malic etc. and I find magnesium sulphate to be very absorbable and comes with the added benefit of sulphur, another essential mineral.