Clench - Shell Stone?

Quoted text begins.Is this stone similar to clench?
End of quote.

The simple answer is NO! Oh, by the way, it's CLUNCH, and it's a chalk.

"The stone is a chalk from the Lower Chalk of Cretaceous age. It is a
greyish white colour often with a greenish tinge. The latter is due to the
presence of glauconite, the potassium and iron aluminium silicate mineral
also found in Kentish Ragstone. The stone has a gritty texture due to the
presence of shell fragments. The stone from the bottom of the face is
considered to be harder and more durable."

Please see :-
http://projects.bre.co.uk/ConDiv/stonelist/camclunch.html
or
http://freepages.history.rootsweb.com/~quarries/articles_and_books/name_and_origin.html
or
[URL now obsolete]

Hope this helps a little, someone else might be able to answer the other
part of your query.
Regards
Tony