Put it under a microscope, if it has little pits it has been acid treated.
John
 
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> From: Robert (Bob) Granda <[log in to unmask]>
> To: [log in to unmask]
> Subject: Re: Green snail
> Date: Saturday, February 13, 1999 10:02 PM
>
> Hello Art,
>         Many years ago at a shell show in Jacksonville, Florida,  Tucker
Abbott and I
> were talking about Papustyla pulcherrima.  I have two specimens that are
> almost totally yellow.  Tucker told me that they could have been treated
with
> acid or the coloration was natural, due to dry or drought weather. Don't
know
> how one would tell if their shell was treated with acid or yellow by
natural
> conditions.
>
> Best Regards,
> Bob
> Panama City, FL