Research On Gemmological Characteristics Of MOCUI(Omphacite Jade) And It’s Quality Influence Factors

As the most precious jade species, Feicui is adored and demanded by the general public because of its various colors, bright luster, fine texture and good toughness, depending on which the distinctive and integrated business chain are developed, including aspects of culture, design, process, supply-demand relationship and brand sales. Meanwhile, it has drawn great interests from the people and is the one of jade species having the most collectable, appreciative and cultural value.Mocui is a special jade species and characterized by the dark and blackish green through transmitted and reflected light, respectively. Currently, the knowledge of Mocui is limited in its main mineral composition of omphacite. The definition in the national standard, however, did not specifies the assemblage of omphacite as the jade. The science matters with quality evaluation and influencing factors of omphacite jade urgently need to be overcome.Here, this study investigates the gem properties, mineral compositions, texture, structure and spectroscopy via general gemmological Characters test, polarizing microscope observation, electron probe microanalysis and infrared-ultraviolet spectrum, depended on collecting representative samples with different textures, colors, transparency and purity and reading the results from home and abroad.The results in this study show that the dark green of omphacite jade has a hue ranges of blue, yellow and brown. Transparency changes from opaque to translucent, with the values of 10% to 25%. The inclusion, lamellosity and crack in the omphacite jade appear as the styles of crumb, floc and spot. The texture of omphacite jade, according to grain size, is classified as inequigranular, porphyroblastic, aphanitic and fine grained one. On the basis of shape of minerals, it is divided into nematoblastic and columnar texture. In addition, it has porphyroblastic metasomatic relict and vien packing texture in their mutual relation. The omphacite jade with high quality has main mineral composition of omphacite, the one with low quality is jadeite or omphacitite with more jadeite composition.Analytical results are compared with the naked-eye and microscope observation. This study has accomplished an exploratory classification according to six influencing factors(texture, transparency, color, purity, process and weight) of all samples. The preliminary assessment guidelines were established.