Portland Stone: the Champagne of stones ...

["Dr. Tim Palmer" <tjp@xxxxxxxxxx>]

Portland Stone comes from the Isle of Portland in
England.  It is a Jurassic Oolitic limestone that is
characterised (in the 2 principal varieties) by a very
uniform grain size and a high porosity between the
grains. These two properties contribute to its excellent
carving properties.  It is pale buff when fresh from the
quarry, and weathers white to very pale grey.

For the last 300 years it has been the principal
building stone for high quality architectural work in
London, England (and in some other cities in the U.K.).
It is also widely used for fine quality internal work.
Two suppliers quarry it on the Isle of Portland: Albion
Stone (sales@xxxxxxxxxxxxxxxxxxxxxxx)and Hanson Bath
and Portland (Bumpers Lane, Portland, Dorset DT5 1HY).
Buy from the producers and cut out the middle men!

Indiana Stone is less even grained (the grains are a mix
of ooliths and shell debris (the latter of which are
bigger and darker than the ooliths)and less porous than
Portland.  The sedimentary bedding is often more evident
than in Portland.

Portland Cement has never been made from Portland Stone.
When the cement production process was patented in the
early 19th C, the product was called Portland Cement
because of the superficial similarity of the set product
to Portland Stone, particularly when it was used as an
external render with ruled lines to simulate coursed
ashlar.

Tim Palmer

Dr Tim Palmer C.Geol., F.G.S.
Executive Officer, The Palaeontological Association
I.G.E.S., University of Wales
Aberystwyth SY23 3DB
Wales, U.K.

Phone/Answerphone: +44 (0) 1970 627107
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Secretary: +44 (0) 1970 627107
E-mail: palass@xxxxxxxxxx
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