I don't believe there are 6 pence coins in circulation anymore. Ireland is on the Euro of course. I don't know if Ireland had a 6p coin, but if the UK was running things in Ireland when the six-pence rule was adopted they did have a 6p coin, but not now that I am aware of. I only saw 1p, 2p, 10p, 20p, & maybe 50p but I'm not too sure on that one.
Here is a 6p coin from 1956 that my dad gave to me:
It is a fairly lightweight coin a little less in diameter than a US nickel and thinner too.