How Much Portland Stone Is Left — Is the Island Still Rich in Reserves?

There has long been speculation about how much Portland Stone remains beneath the Isle of Portland. Despite common misconceptions, the reserves of this world-renowned limestone remain extensive — enough to sustain extraction for centuries to come.

Portland Stone forms a 9-metre-thick layer of limestone that sits above Portland Sands and Upper Kimmeridge Clay, covering the entire top of the island. In total, this amounts to approximately 15 million cubic metres of stone. Over the past thousand years, around half of that has been extracted.

Historically, the stone was collected at sea level from natural landslips, before large-scale quarrying began around 300 years ago following the Great Fire of London. In 2002, Albion Stone revolutionised the industry by introducing mining techniques to Portland, unlocking vast reserves of stone that were previously inaccessible through traditional quarrying.

Thanks to modern technology and more efficient extraction methods, wastage has been dramatically reduced meaning more of the stone extracted can be used in finished products. Even as demand rises and extraction rates increase, these efficiency gains keep wastage low; current estimates therefore still indicate around 700 years of Portland Stone reserves remaining on the island.

Albion Stone currently holds the largest quantity of reserves on Portland, supported by the opening of the new Stonehills Mine. This development alone secures approximately 70 years of future extraction, with the potential to extend operations further through additional mining sites.

Albion Stone is also committed to the long-term stewardship of Portland’s landscape. We are working closely with the local community to restore former quarry sites, re-seeding worked areas with native wildflower mixes to encourage wildlife and natural recolonisation. Ongoing landscaping programmes target invasive scrub species such as buddleia and cotoneaster, removing and managing these plants so native flora can re-establish. Albion Stone is here for the long haul and will continue to collaborate with the Portland community to ensure that Portland Stone is extracted sustainably and with positive environmental outcomes.  Portland Stone has been at the heart of British architecture for centuries, and thanks to careful management, innovation, and sustainable practices, it will continue to be available for many generations to come.

Tags: Reserves