Materials that supply calcium (Ca) and magnesium (Mg)

MATERIAL	% Ca	% Mg	TNP*
Aragonite	37-39	<0.5
Bone meal	23	0.4	60-70
Calcium limestone CaCO₃	32	3	85-100
Dolomite limestone Ca/MgCO₃	22	11	95-108
Epsom salt MgSO₄ · 7H₂O		10
Gypsum CaSO₄ · 2H₂O	23
Kieserite MgSO₄ · H₂O		18
Phosphate rock	24		50
Potassium Magnesium Sulfate K₂SO₄ · 2MgSO₄		11
Wood ashes	23.3	2.2
*Total Neutralizing Power (as % CaCO₃)