(ABC) - Fossil beer is the latest innovation for a South Australian brewer, as more craft beer makers get creative to stand out in a crowded market.

Kangaroo Island brewer Mike Holden is set to release a 'shale ale' beer, commemorating 10 years of fossil research on the South Australian island.

Mr Holden said the ale was filtered through fossil-rich shale that was more than half a billion years old.

"We just thought for this one, why not let the millions of years of shale rock speak for itself and see what comes through?" he said.

"The beer definitely has a unique flavour to it, but it is not something that is off-putting or maybe something that people will not even recognise."