The Bowral trachyte boulder (Mount Gibraltar microsyenite) will now sit alongside unique rocks from all over Australia in the National Rock Garden in Canberra. 

Extracted from Mount Gibraltar in the Southern Highlands in the early hours of Wednesday morning, November 1, the stone was transported to the National Rock Garden in Canberra, where it will be polished and have an inscribed plaque attached. 

The Wingecarribee Shire Council and the Mount Gibraltar Landcare and Bushcare group collaborated to organise the donation. 

Director of the National Rock Garden, Mike Smith, said the site was thrilled to acquire a stone with “considerable historical significance”. 

“We try to put rocks in the garden that tell a story,” he said.

“The Bowral Trachyte has contributed significantly to local industry and influenced the lives of a lot of Australians for a long period of time, and continues to do so.”

”And in addition to being a really nice building stone, it happens to have some very interesting chemical characteristics.”

Bushcare group convenor, Jane Lemann, said Bowral trachyte was a thoroughly underrated natural resource unique to the Highlands. 

“People don’t appreciate quite how special it is,” she said. 

“Mount Gibraltar is the only place in the world where this stone is found.”

Geologically known as ‘microsyenite’, the stone was commercially marketed as Bowral trachyte in the later nineteenth and early twentieth centuries.

The stone’s unique properties, durability, strength and aesthetics made it highly sought after, and a convenient replacement for Sydney’s original crumbling sandstone kerbs and gutters. 

Sydney’s Queen Victoria building, the ANZAC memorial in Hyde Park and the Sydney Cenotaph in Martin Place all feature the Highland stone. 

It was even used in the construction of the Australian Embassy in London. 

Locally, the trachyte can be found in some of the shire’s original residential homes and buildings such as the former Bowral Court House. 

It was also quarried for ballast in construction of the Great Southern Railway line from Mittagong to Goulburn.

Mount Gibraltar, situated between Bowral and Mittagong, is one of the district's most recognisable natural features.

The mountain is a ‘volcanic intrusion’ that cooled in such a way as to form the microsyenite, which was exposed after 180 million years of erosion.