Mineralogical Characteristcis Of The Chambersite And Its Ore Genesis Of Jixian, Tianjin

Chambersite is a rare kind of manganese chlorine borate mineral (Mn3B7O13Cl),Jixian deposit is the only and commercially valuable chambersite independent depositin the world. The particles of chambersite in Jixian are very small (nanoscale) so thatthere are no complete mineralogy information and definitly genetic theory now. Thispaper made a detailed study on the mineralogy characteristics of microgranularchambersite, crystal chemistry and crystal structure. Meanwhile, it conducted themineral synthetic experiments and discussed genesis of the microgranularchambersite.1. The shape of chambersite sampled Jixian is irregular granular,50-200nm, andthe chemical formula is (Mn2.749,Fe0.05)B7.133O13Cl0.984, thereinto the valence ofmanganese and boron element are+2and+3, respectively. The crystal cell parametersis a0=0.8691±0.0001，b0=0.8690±0.0004，c0=1.284±0.0003, orthorhombic system.The phase transition temperature from orthorhombic system at low temperature andcubic system at high temperature is411℃. The interplanar spacing and crystal cellparameters of chambersite in Jixian were both higher than the ones in the mineralogyDatabase.2. This paper found a spiral grain growth hillock and layer growth lines at crystalsurface, so that the author considers that the growth process of Jixian chambersitecrystals accord with the spiral growth mechanism. Boron and manganese atomsposition in the high resolution atomic figure of Jixian chambersite was marked,meanwhile this paper indicates that there were unobvious distinction between crystalsstructure model of chambersite in Jixian and the one in database, which two kinds justhad slightly different cell parameters.3. Chambersite was synthesized by the orthogonal designation in250℃-400℃,weak acid and high chloride environment, and the best forming conditions are400℃,CCl-/CMn2+=2.5, and pH=6. In these three factors of influence, temperature is themain factor. 5. According to the geological characteristics of the Jixian deposite area and themicrogranular chambersite mineralogy research, the paper indicates that the mainsource of boron and manganese are related to submarine volcanic eruption, andore-forming temperature was less than400℃. Weak acidity, high salinity andanaerobic environment are favored to ore-formation and chambersite in Jixian formedin submarine hydrothermal sedimentary.