Hull Geological Society
Common urban rocks -
"Granites and Marbles"
In the masonry trade, and for worktops too, there tend to be two sorts of Rock - Granite and Marble. The term Granite is used for igneous rocks and the term Marble is used for everything else including sedimentary rocks. The rocks tend to be given trade names such as Baltic Brown and Balmoral.
To a Geologist a Granite is a specific plutonic igneous rock which contains crystals of quartz, feldspar and some darker minerals. The term Marble is used for a limestone that has been metamorphosed causing the recrystallization of the mineral calcite (an example often seen in cemeteries as a gravestone is Carrara Marble from Italy) . The Marble may also contain other minerals giving it a green or pink colour. In the past some sedimentary limestones have been given the stratigraphic name such as the Forrest Marble - these days this would not be done and stratigraphers are encouraged to name strata from a type locality or area.
Copyright - Mike Horne and Hull Geological Society 2020
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