Lead is one of the earliest ls that man extracted from lead and zinc mine. It is one of the softest heavy ls, but also one of the largest proportion ls, with blue-gray, hardness 1.5, specific gravity 11.34, melting point 327.4℃, boiling point 1750℃, good ductility, easy to alloy with other ls (such as zinc, tin, antimony, arsenic, etc.).
       Zinc was the last of the seven ancient non-ferrous ls (copper, tin, lead, gold, silver, mercury, zinc) to be extracted from lead and zinc mine later. Zinc l is bluish white, hardness 2.0, melting point 419.5℃, boiling point 911℃, when heated to 100 ~ 150℃, it has good compression, calended specific gravity 7.19. Zinc can be made of alloy with a variety of non-ferrous ls or zinc alloys, among which the most important is zinc and copper, tin, lead and other components of brass, but also aluminum, magnesium, copper and other components of die casting.