摘要
千山黄冻石是近年新发现的一种温润致密,颜色棕黄色-黄褐色,具有很高工艺价值和经济价值的斜绿泥石质玉,其原生矿脉以巢囊状、透镜状、似层状赋存于辽河群大石桥组三段地层中。已开发利用的次生独石围绕原生矿脉分布在附近数千米内的山间冲沟、河道两侧的农田及残积、洪冲积层内。研究表明,千山黄冻石的主要矿物组成为极富镁贫铁的斜绿泥石,微量矿物有石英、金云母、滑石、金红石等。受控于主要矿物的化学成分,玉石的岩石化学特征表现为富镁而贫铁;其稀土总量很低,轻重稀土分馏程度也较低;相对于原始地幔,大离子亲石元素K、Ba、Sr不同程度亏损;高场强元素Nb、Ta、Zr、Hf、Th、U、Ti趋向于富集。千山黄冻石不应称为“田黄”;因主要组成矿物不同,红外光谱等大型仪器的矿物物相鉴定能有效区分千山黄冻石与田黄。另外,同产区外观相似的,但主要组成矿物为非斜绿泥石的蛇纹石、滑石、碳酸盐质玉石,不能称为千山黄冻石。
Qianshanhuangdong stone is a mild, dense, brownish-yellow to yellowish-brown clinochlore jade that has been discovered in recent years with high artistic and economic value. Produced in Section 3 in the Dashiqiao Formation, Liaohe Group, the primary Qianshanhuangdong stone occur as nested, sac-shaped, lenticular, and quasi-lamellar orebodies. The secondary monoliths that have been developed and utilized are distributed in the alluvial-pluvial deposits and farmlands on both sides of the gullies and riverways around mountains of the primary mineral veins several kilometers nearby. The research show that Qianshanhuangdong stone mainly consists of clinochlore, which is extremely rich in Mg and poor in Fe, and contains trace minerals such as quartz, phlogopite, talc, rutile, etc. Due to the chemical composition of the main mineral, the petrochemical characteristics of the stone are correspondingly rich in Mg and poor in Fe;the total amount of rare earth in Qianshanhuangdong stone is extremely small, and the degree of fractionation of light and heavy rare earth is also low. Compared with the primitive mantle, the large ion lithophile elements K, Ba, and Sr of Qianshanhuangdong stone have different degrees of loss;high field-strength elements such as Nb, Ta, Zr, Hf, Th, U, and Ti tend to be enriched. Qianshanhuangdong stone should not be called Tianhuang because of their different main constituent minerals. By the quantitative phase determination of minerals with large instruments such as infrared spectroscopy, it can be effectively distinguish Qianshanhuangdong stone and Tianhuang. Although there are some stones that mainly consist of serpentine, talc, or carbonate from the same origin and are somewhat similar to the clinochlore one in appearance, they still cannot be called Qianshanhuangdong stone ever.
作者
李冰
王长秋
LI Bin;WANG Changqiu(Key Laboratory of Orogenic Belts and Crustal Evolution,MOE,School of Earth and Space Sciences,Peking University,Beijing 100871,China;Gem Appraisal Center of Peking University,Beijing 100871,China)
关键词
千山黄冻石
斜绿泥石
田黄
印章石
Qianshanhuangdong stone
clinochlore
Tianhuang
seal stone
