NAGT Rock and Mineral Exchange - Available https://nagt.org/nagt/teaching_resources/exchange/index.html Petrology Samples https://nagt.org/nagt/teaching_resources/exchange/postings/126651.html Fri, 19 Feb 2016 00:00:00 -0600 https://nagt.org/nagt/teaching_resources/exchange/postings/126651.html ophiolite, Tertiary sedimentary, misc metamorphic https://nagt.org/nagt/teaching_resources/exchange/postings/147401.html Mon, 11 Jul 2016 00:00:00 -0500 https://nagt.org/nagt/teaching_resources/exchange/postings/147401.html