Hello,
My comments too:
At 12:31 PM 2/13/03 +0000, you wrote:
>As Tim says dolerite is a fine-grained intrusive gabbro.
All gabbros are intrusive, only basalts may be both intrusive or extrusive.
>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
In Aus, they commonly also refer to blocks of basalt (and/or finer-grained
dolerite) as "Bluestone" when used in buildings or as curb-and-guttering, as
was the case here centuries ago (but no longer current practice anywhere).
"Trap" has rarely been used in Aus and only by archaic type geologists
(probably trained in England) and not by the general population.
Kind Regards,
John
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