From:
"Dr. Tim Palmer" <tjp@xxxxxxxxxx>
Date:
Mon, 24 Jun 2002 10:10:17 +0100
Subject:
Nodule in Limestone
Hi Tony and all,
This sounds like a pretty good description of a
marcasite/pyrite (iron sulphide) nodule, but I'm sure
you are right about it not being Portland, which is very
low in iron impurities (because it didn't support the
right sort of bacteria in the decades following its
deposition). I have never seen sulphide concentrations
in Portland (neither in blocks, nor in the quarries).
The vein sounds like a calcite vein (common in some of
the Bath stones). These do indeed have larger ooliths
than Portland, and the oolitic structure is much more
evident (reasons for this will be published later on
this year; I'll post a copy to the group).
Tim
Dr Tim Palmer C.Geol., F.G.S.
Executive Officer, The Palaeontological Association
I.G.E.S., University of Wales
Aberystwyth SY23 3DB
Wales, U.K.
Phone/Answerphone: +44 (0) 1970 627107
Fax: +44 (0) 1970 622659
Secretary: +44 (0) 1970 622643
Web: http://www.palass.org/
- References
- message 00028: Nodule in Limestone - Beverley Wright (24 Jun 2002)
- Previous by Thread: message 00030: Nodule in Limestone - Peter Hill (24 Jun 2002)
- Next by Thread: message 00032: Nodule in Limestone - John VanCamp (25 Jun 2002)
- Previous by Date: message 00030: Nodule in Limestone - Peter Hill (24 Jun 2002)
- Next by Date: message 00032: Nodule in Limestone - John VanCamp (25 Jun 2002)
