Study On The Formation And Coupling Analysis On Gemology And Mineralogy Characteristics Of The Huanglong Jade (chrismatite) From Longling County, Yunnan

The Huanglong Jade (Chrismatite) of Longling, Yunnan, which has delicate andexquisite texture, and had been honored as Siliceous Tianhuang, is a new type of highquality chert jade appeared lately years in the Chinese jade market. The HuanglongJade occurs mainly in contact zone or tensile cracks of upper granite and slate ofGongyanghe Group (Triassic). Its secondary ores are distributed along the river bed,flood plain and fields of the Supa River.Field observation and modern test technologies have been used in this paper, tomake a systematic study on aspects of geochemical and petrological characteristics ofHuanglong Jade (Chrismatite). Furthermore, coupling analysis is done on the basis ofprevious studies to make a connection between its gemology and mineralogycharacteristics. In this thesis, texture types, group, evolution characteristics have beenstudied under polarizing microscopy. Geochemical characteristics of minor elements,and REE have been detailed studied, and revealed that formation of the HuanglongJade is mainly related to atmospheric precipitation, and hydrothermal fluids also takepart in its formation.The main siliceous mineral constituent of Huanglong Jade, aphanitic quartz，chalcedony, microcrystalline quartz and mega quarz, whose are characterized byvaried crystal form and size, have been showed different texture element features.From the microscope we can tell that the structure of the Huanglong jade is mainlyaphanitic to particulate structure, and it also contains phanerocrystalline, fine-grainedand macrograin type. The analysis of X-ray diffraction and infrared shows that themineral composition of the Huanglong Jade is mainly quartz, and also containing asmall amount of muscovite, dolomite and clay minerals of iron. And for the first timethe author discovered that finely dispersed kaolinites are contained in the HuanglongJade, which contributes greatly to the excellent quality of it. The Jade sample have showed negative anomalies and not clear anomalies ofδCe, even positive anomalies of δCe. The value of δEu is weak positive anomalies,which reveal the genesis of atmospheric precipitation sedimentation. The abovedistribution characteristics of main and REE have been argely controlled by theoriginal depositional environment and the activity grade of ore-forming fluid.Three variables, body colour, structural diversity, types and content of thesecondary minerals are the three major factors related to the quality of the HuanglongJade. The original ore, which resulted in combined actions of sedimentation,weathering and eluviation, formed in the open fracture environment of subsurface.Secondary ore is formed by subsurface effect (including biological weathering,chemical weathering and actions of water), which changed the appearance of theoriginal ore greatly and enriched the variety of the Huanglong Jade.