Like many pteriomorphians, Spondylus has an outer shell layer of
calcite and inner layers of aragonite.  Inner layers are crossed
lamellar; outer layer is foliated.  See Carter, 1990 (Skeletal
Biomineralization) for lots of detail.

--
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"

----------------------------------------------------------------------
[log in to unmask] - a forum for informal discussions on molluscs
To leave this list, click on the following web link:
http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1
Type your email address and name in the appropriate box and
click leave the list.
----------------------------------------------------------------------