Study On Geologic-geochemical Property And Metallogenic Regularity Of Nephritic Ore In Luodian County,Guizhou Province

Luodian Jade, a kind of nephrite, was first discovered in Guizhou province, which was researched in some respects, and many results have been achieved until now. However, most of these results based on gemological-mineralogical characteristics, and some understanding need to be obtained on the deposits geological features, formation conditions, the genesis and distributing characteristics. Therefore, on the basis of the previous studies and the scientific achievements,ore deposit geology is researched a lot in this study. In this paper, based on extensive field investigation, polarization microscope, scanning electron microscope,X fluorescence spectrograph and other modern testing methods are used, together with geochemical data, thereby analyzing its mineral composition, texture and chemical component,and then some new understanding are obtained on the genesis, ore-controlling factors and metallogenic regularity.(1) Luodian Jade exists in the contact zone of diabase and Permian limestones in the Sidazhai formation. Its ore body, in the shape of stratiform, stratoid, lentoid and irregular crumby, was found in the zone of silicalites or marbles. The colors of Luodian Jade include white, green,bluish-white and spotted jade, and the spotted jade is mainly consist.(2) Tremolite is the major mineral composition of Luodian Jade, which content in commonly is more than 90%, in the shape of fiber, and its aggregation is wispy and radial. The texture of tremolite is complex, containing fibrous interlaced texture, fibrous-panniform crystalloblastic interlaced texture, fibrous-columnar crystalloblastic texture and columnar interlaced texture.(3) Two types of Luodian nephrite mineralization were discovered. One type is caused by banded silicalites’ hydrothermal alteration: SiO2 in banded silicalites is driven by the magma thermal, metasomatism with CaO and MgO in limestones, and then tremolites are formed from these compositions in proportion. Another type results from limestones’ hydrothermal alteration:marbles are generated in the first phase, and tremolites form in the second phase.(4) Mineralization is controlled by stratum and rock mass. Furthermore, nephrite in the south is better than the north. Maybe better nephritic ore can be found in the contact zone of diabase and limestones in the south of Luodian, Wangmo and northern Guangxi.