As Tim says dolerite is a fine-grained intrusive gabbro.Mineralogically it
should have a plagiocalse feldspar that is at least labradorite in
composition (ie very calcic) and there should be more clinopyroxene than
orthopyroxene otherwise it becomes a micronorite.The old name for dolerite
is Whinstone but then that is the old name for many other resistant rocks.
On old names trap is the old name for basalt as in Deccan Traps.
cheers
Rob
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