Study On Mineralogy And Gemmology Of Balin Stone

Balin Stone is one of the "Chinese Famous Stones " with sleek texture, flowery color and various category, and is well-known at home and aboard. This thesis has done some research on mineralogy, gemology, petrochemistry and deposit genesis of Balin Stones by modern testing methods. So the Balin Stone's study will be more systemic and scientific.Study on mineral composition indicates that the main mineral compositions of Balin Stone are ordered kaolinite, ordered dickite and trasitional minerals of kaolinite and dickite. The HL and A/B have been calculated to testify the structural order is higher when mineral compositions are kaolinite and dickite, but lower when it's kaolinite's and dickite's trasitional minerals. We have discovered the main mineral compositions of some samples which are called "Hard Stone" by indigene are alunite and quartz. It is too hard to be carved.The "roe gel", "float grass gel" and "chicken-blood stone" is rare and costly. Study on subordinate mineral indicates that the "roe" in "roe gel" is diaspore, the "float grass" in"float grass gel" is hematite and black cinnabar, the "blood" in "chicken-blood stone" is cinnabar and the black and opaque mineral in Balin Stone is mainly pyrite.Having mensurated the basal gemological characters, on the basis of which classified and named Balin Stone systematically and suggested to name Balin Stone artworks with "category and subject matter". Quality evaluation indicates different evaluation factors with five categories.Colouration mechanism is studied to explain that white Balin Stone is pure kaolinite mineral with little colorgenous elements. Lots of hematites exist in red Balin Stone and work for redness, whereas, the pink is due to the isomorphous substitution of Fe and Mn. Abundant limonites occurring in intergrain can explain the yellowness, and Fe³⁺ can enter into crystal lattice to help for yellowness by electron transition and charge transfer. Black and opaque pyrites in Balin Stone induce blackness.Transmissivity test, scanning electro-microscopy observation and grain size analysis are adopted to study the influencing factors of transparence. The results show that average grain size and main mineral composition are the influencing factors of transparence to light-colored Balin Stone. The smaller average grain size and the purer main mineral composition are, the better transparence is. But to chromatic Balin Stone, dark and opaque subordinate minerals are the main influencing factors of transparence.Analysis of regional petrochemistry shows that regional volcanic rocks belong to the cale-alka-line series of subalkaline series. Characters of petrochemistry indicate regional magma generates fractional crystallization or assimilation and contamination. REE analysis and homoplasy of chondrite-normalized REE patems of Balin Stones and its surrouding rocks indicate that rhyolite is Balin Stone's source of ore-forming materials.Balin Stone deposit is proved to be hydrothermal ore deposit by testing the hydrogen and oxygen isotopic compositions of Balin Stone. The ore-forming temperature is estimatedto be from 200℃ to 230℃ and mineralizing fluid is derived from meteoric water. The mineralization associates with volcanic hydrothermal alteration which has been experiencing a long and complicated process. Silicification, alunitization, kaolinization and pyritization are the important exploration indications to Balin Stone, and cinnabaration and pyritization are the exploration indications to Balin Chicken-blood Stone.The dumortierite rock is cobalt blue and blue-purple, and it's a new discovery at Baiyinshana east to Balin Stone mining area. The mineralogical research was made by electronic microprobe analysis. X-ray diffraction and IR spectra to confirm it is composed of particulate quartz, dumortierite and pyrophyllite. The dumortierite rocks belong to a new category of Balin Stone.