Jim Constant wrote:
I would like to find out the chemical structure of the conch shells.
Where should I address myself to obtain this information.
 
Hi Jim,
 
I'm kind of surprised no-one has tackled this one after a couple of days, so
I'll give it a shot.  The shells of almost all molluscs, including "conch
shells" are composed almost entirely of calcium carbonate (CaCO3).  However,
the compound may be present as either, or both, of two separate forms, which
are chemically identical, but which belong to different systems of
crystallization.  The first form has a prismatic crystalline structure, and is
analygous to the mineral calcite.  The other form has a lamellate structure,
and is analygous to the mineral aragonite.  Most gastropod shells consist
primarily of multiple layers of aragonite, with the crystalline orientation
differing in each subsequent layer, with minor percentages of calcite.  Some
shells (Helix, Viviparus) are entirely aragonite.  But a few forms (Epitonium,
Janthina) are almost entirely calcite.  Small amounts of other salts are often
present in the calcium carbonate matrix, the commonest being calcium
phosphate, followed by calcium nitrate and magnesium carbonate.  Trace amounts
of many other salts can often be found as well.  In many shells, there are
extremely thin layers of organic matter, termed conchiolin, between the
aragonitic lamellae.  I believe conchiolin is often referred to by the shorter
name conchin these days.  The rest of the shell chemistry is pigment
chemistry, which is considerably more complex than the structural chemistry.
That's sketchy, but it's the best I can do.  Hope it helps.
 
Paul Monfils