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PPL Vesuvianite
(idocrase)-rich contact altered limestone. Oxford Limestone in
upper contact of the Whin Sill dolerite. Barrasford Quarry,
Barrasford , Northumberland, NY919 749 Collected by B. Young 2005 |
XPL The near centre vesuvianite (idocrase) crystal shows typical low order grey interference colours and is surrounded by calcite. The vesuvianite to the left is in the extinction position. Large isotropic garnet centre right and smaller ones seen towards top centre. |
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The hand specimen shows pink garnets (grossular) and
dark carbonaceous material set in a calcium carbonate groundmass. The
vesuvianite (or idocrase) is apparent only in the thin section.
Vesuvianite occurs in thermally metamorphosed limestones and in
skarns. It is associated with grossular, a calcium bearing garnet as
well as diopside and wollastonite. |