NAGT Rock and Mineral Exchange - Available http://nagt.org/nagt/teaching_resources/exchange/index.html Fossilized rouse and massive limestone http://nagt.org/nagt/teaching_resources/exchange/postings/81067.html Thu, 20 Mar 2014 00:00:00 -0500 http://nagt.org/nagt/teaching_resources/exchange/postings/81067.html Rock specimens for trade http://nagt.org/nagt/teaching_resources/exchange/postings/89521.html Mon, 18 Aug 2014 00:00:00 -0500 http://nagt.org/nagt/teaching_resources/exchange/postings/89521.html