Hey Andrew,

You might enjoy the upcoming issue of American Conchologist.  We have an
article about the deep sea gastropod from the Indian Ocean with iron pyrite
"armor" covering the soft body parts.  The metal overlays a chitinous inner
core and covers the body in overlapping plates.  The plates are black when
the animal is first recovered from the sea but turned reddish with rust
after being immersed in lab ethanol.  The article has some nice photographs
of this unique mollusk.

The black layer you refer to on neritids and thiarids from Fiji is also
found on neritids from other areas.  It is easily mistaken for periostracum,
but as you mention, it actually covers the periostracal layer.  It does not
seem to dissolve in bleach like the organic periostracum.

Tom E.

-----Original Message-----
From: Conchologists List [mailto:[log in to unmask]]On Behalf Of
Andrew Grebneff
Sent: Monday, January 03, 2005 9:20 PM
To: [log in to unmask]
Subject: Re: Ferruginous layer


>Hi all,
>I often find living mollusc specimen partially covered with a thin
>ferruginous layer.
>I tried to get some papers on that matter, but I failed.
>Does someone knows the meaning of such layers and some bibliography also?
>Thank you all in advance:
>Regards
>Enzo Campani

Shells living where rust is present will often be ruststained, but
this is nonbiogenic...

The only shells I find which might have iron compounds deposited are
freshwater ones from the tropics (Fiji), where I have collected
neritids and various thiarids with a thick black (probably
nonferrous, possibly organic) smooth coating. This is easy to remove
by bleaching, as it is deposited on top of the periostracum, which
dissolves, releasing the black layer in slabs).
--
Andrew Grebneff
Dunedin
New Zealand
Fossil preparator
<[log in to unmask]>
Seashell, Macintosh, VW/Toyota van nut

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