A large slab of pounamu, or greenstone, has been handed in to police after being found in bush in a small town in the Bay of Plenty. 

Waikato Police say a member of the public brought the valuable piece of stone in to the Hamilton Police station. 

Authorities took to social media networking site Facebook to appeal to anyone who may have any information as to who may own the pounamu. 

Police said: "The hope [is] it can be returned to its owner." 

The pounamu is about 60cm high and 20cm wide at its widest point. 

Police say there is also something painted on one of it - but which will need to be described or identified to authorities. 

Police say a member of the public handed the valuable greenstone in at a local police station. Photo / NZ Police 

Exactly where the greenstone was found in Te Kaha has not been identified by police other than to say it was found in vegetation. 

A pounamu carver told the Herald it would be difficult to gauge given there were various factors - including its grade and purity - that were taken into account and could not be entirely determined by looking at a couple of photos. 

One thing that was certain, however, was that it had been in someone's possession at some point, he said. 

"It certainly has had human hands on it. It's been cut down the middle - you can see it in the photo." 

Several members of the public commenting on the Waikato Police Facebook page say it may have in fact been a memorial at the site and are calling on authorities to return it. 

"Take it back to where it was found - sacred tapu," one woman writes. 

Anyone with information about the greenstone is encouraged to call Police on 105