What is Australian 50 cent double bar fault?

Answer 1

The "double bar" refers to two lines appearing to stick out horizontally from the back of the emus head. They are actually a part of the reed design. The fault is most pronounced on the 1979 and 1980 50 cent coins and to a lesser degree on the 1966 (round) coin. It was a weak spot on the dies and caused early fractures in the coins. The offending part of the design was subsequently ground out of the dies and is not visible in later coins. An Australian 1979 50 cent coin (Double Bar fault), uncirculated and in absolute mint condition could fetch up to $12 AUD. An Australian 1979 50 cent coin (Double Bar fault)(Proof), uncirculated and in absolute mint condition could fetch up to $100 AUD. An Australian 1980 50 cent coin (Double Bar fault), circulated but still in good condition, might fetch anything up to $4 AUD. A reputable coin dealer will be able to give a more accurate valuation.