Mineralogical Study Of Main Associated Minerals In Jadeitite Jade From Myanmar

The gem grade jadeitite jade material which are proven in the world are producted in Myitkyina Kachin State where is in northern Myanmar. Myanmar jadeitite jade which dominantly consists of jadeite are aggregate of a variety of minerals. The main associated minerals are kosmochlor, omphacite, amphibole, feldsparand and some metallic minerals. It has a great significance to research associated minerals for making clear the structure and texture, product quality and formation conditions of Myanmar jadeitite jade. This paper studies and analysis the chemical composition, structure and texture, mineral association and paragenetic sequence of the main associated mineral in Myanmar jadeitite jade, such as chromite, kosmochlor, omphacite and other minerals.A detailed study has been carried out on the representative samples through micropolariscope observation and mordern testing methods such as electron probe microanalysis (EPMA), and FT-IR spectra analysis, and the results are summarized. The results show that: chromite which is in Myanmar jadeitite jade is primary associated minerals, and is the source of Cr3+ in kosmochlor and chromium jade, and also is the cause of green jade appearance. There are higher galaxite contents in the chromite of some Jade samples, up to 12%~15.8%. Metasomatic replacement usually occurred along the edge or the internal cracks and fissures of bright green kosmochlor, which given metasomatic relict texture chromite. It shows that chromite is early mineral, and the formation of kosmochlor at the same time or slightly later than the formation of main jadeite. There are primary chromite and green kosmochlor reaction rim around the chromite in associated amphibole also. It shows that there are processes of Cr3+ diffusion. Jadeite and omphacite usually appear girdle structure or regional exsolution, which show that omphacite is the product of jadeitic fluids riching in calcium, magnesium under the instability crystallization conditions, such as the instability temperature and pressure. After the main formation of the Myanmar jadeitite and associated amphibole, when experiencing late geological transformation jadeitic fluids filled the internal cracks and fissures of amphibole and jadeitization and completed jadeitization or omphacization. "Blue flower" Jade is an important species in Jade. Through this research we confirmed that the "blue flower" mainly is alkaline amphibole, calcic amphibole and sodic-calcic amphibole, which is the product of late metamorphism.