The original query was posted onto the conservation-research list by Kathy Hall (Institute of
Nautical Archaeology, Bodrum). The following answer (forward on by Martin Reed) was sent to the
conservation list by Tim Palmer.
> ------- Forwarded Message Follows -------
> Date: Thu, 18 Jan 2001 22:05:19 +0000
> Reply-to: The conservation-research list <[log in to unmask]>
> From: "Dr. Tim Palmer" <[log in to unmask]>
> Subject: Re: marine ceramic
> To: [log in to unmask]
>
> Cathy,
>
> I answer as a carbonate sedimentologist who has worked extensively on early
> sea-floor lithification by carbonate precipitation.
>
> Sounds like a CaCO3 cement that has been precipitated within a microcrack
> of the ceramic, and which has further exerted a cracking force by its
> growth (see geological literature on tepee structures formed by crystal
> growth in sea-floor cementation environments. Probably aragonite or High
> Mg calcite, possibly under bacterial action. Crystal morphology should
> distinguish between the 2 (aragonite is acicular; Mg calcite stubby or
> 30-50 micron peloids).
>
> If this is the correct answer, then this phenomenon is an entirely natural
> geological process, more often see in marine hardgrounds and sea-floor
> nodules. It is a consequence of the environment, not of the host material.
>
> Pottery has been found incorporated into hardgrounds in the Persian Gulf.
>
> Tim Palmer
>
> At 08:20 18/01/01 +0200, you wrote:
> >Hi all,
> >
> >We have an interesting ceramic phenomenon, and were wondering if anyone has
> >seen anything similar.
> >
> >A pithos raised intact from a marine site where it had spent the past 3000+
> >years was broken in an accident in the Bodrum Museum. The ceramic walls are
> >on average at least 2cm thick and the fabric is fairly high fired, dense
> >and non-porous.
> >
> >Looking at the break edges, running parallel to the surfaces, roughly in
> >the middle of each sherd is an almost continuous layer of white, opaque
> >mineral deposit approx 1mm thick. A sample of this deposit reacts strongly
> >with dilute HCl.
> >
> >The deposit has caused many of the sherds to delaminate into separate
> >exterior and interior surface fragments.
> >
> >My question is, has anyone seen such a phenomenon before in a ceramic?
> >What would you ascribe it to?
> >We are wondering about manufacturing processes or factors relating to
> >burial and recovery.
> >
> >Apologies for cross posting,
> >
> >
> >Kathy Hall
> >
> >Conservator
> >Institute of Nautical Archaeology
> >Bodrum, Turkey.
> >
> >
> 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
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> Web: www.palass.org
> **********************************************
> Martin Read
> Institute of Marine Studies
> University of Plymouth
> e-mail:[log in to unmask]
> http://hydrography.ims.plym.ac.uk
>
> 'Only when the last tree has died
> and the last river been poisoned
> and the last fish been caught
> will we realise we cannot eat money'
> Cree quote
>
> **********************************************
--
_____________________
Ian Oxley MSc MIFA FSA Scot,
Centre for Environmental Resource Management
Dept of Civil & Offshore Engineering,
Heriot-Watt University,
Edinburgh EH14 4AS
Tel. +44 (0)131 449 5111 x4438
mobile 0785 559 9251
Fax. +44 (0)131 451 5078
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