In a previous entry about brockages I discussed briefly how they were formed. I also mentioned that Australian pre-decimal brockage coins can be hard to come by. Fortunately I’ve been able to obtain an image of a nice example of a 1942I Half Penny brockage error coin.
You can see above that the obverse of the coin has been struck normally while the reverse has an incuse image of the obverse. This has happened because a previously struck coin has become stuck to the reverse die and while stuck there this die cap has actually struck the coin blanks rather than the reverse die striking them. Of course the die cap has a properly struck obverse and it is this obverse that has struck the coin above forming the incuse image. This coin is likely an early striking from the die cap as the incuse image is struck well (and in fact might be a better strike than the obverse).