Dear Bill, A good technique to observe changes in calcite or aragonite crystal structures and small compositional changes is by use of cathode luminisence (CL) techniques, which is done on thin sections. OK, you need specific tools for that, but I am certain there are some labs around who can help you with that. Maybe there are some on this list who can suggest a good nearby place for you! About your statement on the ark and titanic: You're right with the ark, they were amateurs and produced something new and even got it published - try that nowadays...... Even to get published a new design as was the Titanic might give problems to publish. But I support your vision - if nobody tries new things we come to a standstill, don't we? I just wanted to put my finger on this small fact most of you will recognize. Pier de Groot **************************************************************************** ******* Temporary address: Professeur Invite Universite Jean Monnet Departement de Geologie 23 rue du Docteur Paul Michelon F-42023 Saint-Etienne Cedex 2 France Permanent address: University of the Witwatersrand EGRU - Department of Geology Private Bag 3 2050 Johannesburg South Africa e-mail: [log in to unmask] **************************************************************************** *******