The Austerfield Mosaic Reserve is popular with school groups, birdwatchers and families, some of whom can need a bit of help finding their way around the extensive 70 acre site.
But with the risk of traditional waymarkers falling victim to vandals, something a little more substantial was needed.
Which is why trust chairman Sue Rose contacted Sibelco whose nearby Warmsworth Quarry produces limestone.
Now she has 20 boulders at her disposal, each weighing a tonne or more, and which will soon be located at key points around the reserve.
“This is a wonderful donation and I’m so grateful,” said a delighted Sue.
“If we’d had to buy the stone and pay for delivery it would have cost about £1,000 and money is always tight.
“The vast majority of people who visit the reserve love and cherish the place but sadly we do have think about vandalism and there’s no way these boulders can be stolen or seriously damaged.
“We’ll have them marked with arrows and once in place I should think they would be here for generations to come.
“Sibelco has also offered to help update our leaflets and other publications, demonstrating that support for groups like ours can be given in many ways.
“I’m so glad I made contact and look forward to a long and rewarding relationship with the firm.”
Sibelco’s UK Operations Manager Adam Daniels said: ‘It’s a privilege to be in a position to help Sue and the other Mosaic volunteers who do so much on behalf of their community.
“We can’t always hand out cash when asked but if we can share our resources, expertise and experience then that’s something we’re always keen to consider.
“The reserve is a great asset to the area and we’re proud to be associated with it.”