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桂林“鸡血红碧玉”是一种石英质玉石,颜色以鲜艳的红色与黑色为主,质地坚硬且耐磨。目前对该矿石的野外产状、地质背景、岩石结构和颜色成因等相关研究报道较少。野外勘察表明,桂林“鸡血红碧玉”矿床位于扬子板块与华夏板块交界处,产于广西北部龙胜地区新元古界丹洲群三门街组经含铁氧化物浸染的汽水热液浅变质砂岩中,其形成过程受到了新元古代-三叠纪数次大地构造与岩浆活动的影响,成因复杂。本文利用偏光显微镜和X射线衍射分析等手段,对桂林“鸡血红碧玉”的成分进行了深入研究,结果表明桂林“鸡血红碧玉”主要矿物组合为石英和赤铁矿,部分样品中含有白云石。石英呈现他形等粒结构和自形变斑晶结构;自形石英颗粒中可见加大边,指示后期经历过变质交代作用。赤铁矿在样品中呈现3种形式产出:1呈单晶形式产于石英颗粒的粒间与晶内;2呈点尘状包裹于石英颗粒中;3呈浸染状分布于石英颗粒间隙。赤铁矿中铁离子为红色致色原因。电子探针分析显示,浸染状和单晶赤铁矿中铁含量高达78.9%~85.6%;点尘状赤铁矿由于颗粒细小,难以精确分析其铁含量。结合石英和赤铁矿发育期次,认为“鸡血红碧玉”中不同形态的石英和赤铁矿的产出与区域地质演化背景相一致。
Guilin “chicken blood red jasper” is a quartz jade, the color of bright red and black-based, hard and wear-resistant texture. At present, there are few reports on the field production, geological background, rock structure and color of the ore. The field survey shows that the Guilin “chicken blood red jasper” deposit is located at the junction of the Yangtze Plate and the Huaxia Plate and is produced in the Sanmenjie Formation of the Danzhou Group in the Neoproterozoic in the Longsheng area in northern Guangxi Province. The iron- In the super-metamorphic sandstone, the formation process was influenced by several tectonic and magmatic activities during the Neoproterozoic-Triassic period, with complicated causes. In this paper, the composition of Guilin “chicken blood red jasper” was studied by means of polarizing microscope and X-ray diffraction analysis. The results showed that the main mineral assemblages in Guilin “chicken blood red jasper” were quartz and hematite, and some samples Contains dolomite. Quartz presents the shape of his meta-granular structure and self-deformation of the phenocrystal structure; self-shaped quartz particles can be seen to increase the edge, indicating that late metamorphic metasomatism. Hematite in the sample showed three forms of output: a single crystal was produced in the form of quartz particles between grain and crystal; 2 was a dust-like particles wrapped in quartz particles; 3 were disseminated in the distribution of quartz particles in the gap. Iron ions in hematite cause red color. Electron probe analysis showed that the content of iron in disseminated and mono-crystalline hematite was as high as 78.9% -85.6%. The spot-dust hematite was difficult to accurately analyze the iron content due to its small size. Combined with the developmental stages of quartz and hematite, it is considered that the output of different forms of quartz and hematite in “chicken blood red jasper” is consistent with the background of regional geological evolution.