Common metals and their alloys; common metals in the nature of heavy metals; materials of metal for railway track construction; [ non-electric cables and wires of common metal; ironmongery in the nature of small items of metal hardware, namely, boring bars in the nature of metal drill pipes for use in well boring; pipes and tubes of metal; unwrought and partly wrought common metals; ] all of the aforesaid being wholly or principally tungsten or alloys of tungsten