The fifty cent piece was originally a circular high silver content coin slightly larger than the 20 cent piece.
It was only issued in 1966 (there are patterns but they are at the RAM) and was withdrawn because the silver content rose to a value of $7 and coins were being hoarded, melted, taken out of the country etc. It was also too easily confused with the 20 cent piece.
A dodecahedronal (10 sided) replacement was first issued in 1969 and has stayed in production since.

There are 4 main obverses -- 1966; 1969 to 1984, 1985 to 1998, 2000 onwards. There was a one off effigy for specially minted 2000 Royal visit coins

There have been numerous Reverses but for the moment I'll just post the different Coats of Arms including those for 2001 States and Territories in the Centenary of Federation


1966 Reverse - Coat of Arms


1969 Reverse - Coat of Arms

2000 - Millenium Incused Union Jack in Flag


2000 - Royal Visit Reverse

2001 - Federation Coat of Arms


2006 - Standard Coat of Arms on 50 cent pieces

2001 - Centenary of Federation State Coat of Arms - New South Wales


2001 - Centenary of Federation State Coat of Arms - Norfolk Island

2001 - Centenary of Federation State Coat of Arms - Northern Territory


2001 - Centenary of Federation State Coat of Arms - Victoria

2001 - Centenary of Federation State Coat of Arms - Western Australia


2001 - Centenary of Federation State Coat of Arms - Australian Capital Territory

2001 - Centenary of Federation State Coat of Arms - Queensland


2001 - Centenary of Federation State Coat of Arms - South Australia

2001 - Centenary of Federation State Coat of Arms - Tasmania

Obverses
2001 - Obverse used from 1997 onwards - there are Large Head/small head variations and a pointed A/Blunt A in Australia



1995 Obverse - used from 1985 to 1996


1966 Obverse

1969 Obverse 69 to 84
1969 Obverse

2000 Royal Visit Obverse

And to round it out, a couple of particularly nice errors

Obverse of 1984 and 1985 Ramstrike errors - the presses have changes and these errors have not occurred since 1985


Reverse of 1984 and 1985 Ramstrike errors

I'm still looking for the Royal Visit coin from circulation but it has proven to be VERY tough! I'll post my other commemoratives later

QX - send me an email and I'll post you one - I have a some spare.

I also realized I haven't put the Accession and Coronation 50's in here.

You put in any you want and I'll fill the gaps

I can see Bluesfil has been busy and I hope he still frequents here.
Just thought I'd chime in with a couple of other items in the 50 cents.

A double clipped 1971....

Last one for the moment....I can hear everybody going thank goodness..
A 1977 Proof 50c.



Don't worry, I'll be back to annoy everybody with more pics....

Here are the rest:

http://www.gxseries.com/numis/austype/aus_decimal.htm#50c

I think I got all of the 50 cents other than the ones only meant for mint sets.

You have done very well, there.
I don't even have a 2007 50c from circulation, yet.

The 2007 50 cents is shockingly difficult to find from circulation. So far I have handled about 10 and the mintage report from last year was at a mere 1.8 million but that was only up to June 2007. Perhaps a bit more were struck later in the years but I am somewhat dubious as I am hearing reporting of people getting 2008 coins - so far I have got a 2008 20 cents coin. Should add that when I have the time.