Wolframite ore (FeWO4) is tin stone in form of impurities and same mass per unit as tin stone. Wolframite is magnetic in nature and tin stone is non-magnetic in nature. They are separated by magnetic separation. Wolframite is attracted by magnet and falls just below magnet while tin stone falls away from it. Roasting and calcination are method for conversion of ore into oxide. Smelting is used for iron.