The water which contains salts of calcium and magnesium, and does not form froth using soap is called hard water.
Salts of calcium and magnesium are sulphate, chlorides, bicarbonates, etc. like,
CaSO4−Calciumsulphate
CaCl2−−Calciumchloride
Ca(HCO3)2−−Calciumbicarbonate
MgSO4−Magnesiumsulphate
MgCl2−Magnesiumchloride
Mg(HCO3)2−Mgnesiumbicarbonate