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Shigar valley gemstones,their chemical composition and origin,Skardu, Gilgit-Baltistan,Pakistan |
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| Authors: | Muhammad Hassan Agheem Mohammad Tahir Shah Tahseenullah Khan Mamoru Murata Muhammad Arif Humaira Dars |
| Institution: | 1. Centre for Pure and Applied Geology, University of Sindh, Jamshoro, Sindh, Pakistan 2. National Centre of Excellence in Geology, University of Peshawar, Peshawar, Pakistan 3. Department of Earth and Environmental Sciences, Bahria University, Islamabad, Pakistan 4. Department of Geosciences, Faculty of Science, Naruto University of Education, Naruto, Tokushima, 772-8502, Japan 5. Department of Geology, University of Peshawar, Peshawar, Pakistan |
| Abstract: | A variety of gemstones is being mined in the Shigar valley, Skardu, Pakistan. These include beryl (goshenite and aquamarine), tourmaline (schorl), garnet (almandine–spessartine), apatite, topaz, fluorite, zoisite, clinozoisite, and axinite, mostly occurring in complex or zoned pegmatites and metamorphic rocks. These have been analyzed using electron probe micro-analyzer and X-ray diffractometer. The mineral chemistry of each gemstone is similar to its respective typical gemstone variety with homogenous chemical composition. Field and chemical characteristics suggest that beryl, tourmaline, garnet, apatite, topaz, and fluorite are occurring in zoned pegmatites which are largely formed by magmatic hydrothermal fluids in the cavities and vugs within the intermediate zone. However, zoisite, clinozoisite, and axinite may have a metamorphic and/or metasomatic origin. |
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