Calcare (Portland)
Gli articoli di riferimento sono in inglese.

An ammonite fossil in Portland stone at the Southwell Landslip, Isle of Portland. Source
Description
Portland limestone comes from the Isle of Portland in Dorset, England. Its pale colour and small rounded grains are characteristic, with fossil shell content varying between beds. These variations influence the surface and the detail available in carving, masonry and architectural work.
History
Portland stone has an established place in British architecture. The continuing identification of individual beds is important to both new work and the matching of stone in historic buildings.
Commissioning
The bed or commercial selection and intended application should be specified. A finish sample should show the expected shell content. Supplier recommendations for a particular bed should be checked against the proposed exposure and use.
