Stone in Archaeology Database

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Caledonian lgneous Supersuite, Northern England Devonian Plutonic Suite.

Varies in colour from brownish red to greyish pink. There are two varieties, 'Dark Shap' which is brownish red speckled with black and light grey minerals and 'Light Shap' which is a much pinker stone set in a greyish matrix.

A hard, crystalline rock which can be variable in texture. It is characterised by its large porphyritic crystals of pink orthoclase feldspar up to 5 cm in length set in a finer groundmass of smaller feldspar crystals, black mica and quartz. Some examples have darker patches known as xenoliths which appear distinct from the original rock.

It is a porphyritic biotite granite comprising orthoclase feldspar (sometimes twinned), plagioclase feldspar, biotite mica, quartz and occasional zenoliths. It can be difficult to distinguish between the two types of Shap petrologically.