和田玉子料“肉”与“皮”的关系初探

A tentative discussion on the relationship between "flesh" and "skin" of the Hetian placer nephrite

通过对大量和田玉子料的表皮及玉肉的观察与分析以及子料薄片的镜下观察与红外光谱分析,对和田玉子料肉"与"皮"的关系进行了探讨。子料有以下几种表皮特征:皮色、"汗毛孔"、"砂眼"、裂纹、礓等,玉石内部的特征有礓、杂质、铁花等。"皮"与"肉"之间存在一定的对应关系,如:"汗毛孔"的大小会反映玉质的粗细;"砂眼"说明内部有不稳定矿物,如黄铁矿出现处会在表皮形成凹坑;礓出现则往往内外相通,礓的分布特征与玉料品质相关,如星点分布,则严重影响玉石的均匀性。和田玉中的主要组成矿物透闪石也可能表现为礓,其在结构上与其周边玉石迥然不同,不同矿物种类,如透辉石、方解石亦可形成礓。裂纹出现并不都是缺陷,有时会形成沿裂隙分布的鲜艳皮色。以上这些对应关系对于和田玉子料的鉴定、评价以及设计加工都有理论或实践意义。当然目前这些还不能表征和田玉"肉"与"皮"的特征以及对应关系的全部,其中对应关系的原因也有待于深入探讨。

By means of microscopic observations and infrared spectroscopic analysis of 'skin' and 'flesh' of cut items of the Hetian placer nephrite,the authors studied their characteristics and relationships.Features of the skin include 'sweat pores',sand hole,crack,stony appearance etc.Inside the skin are stony appearance,impurity,iron flower etc.Some relationships between 'skin' and 'flesh' are summarized as follows:diameter of the sweat pore reflects its host quality:the finer,the better.The sand hole indicates weaker-weathered or softer minerals in the interior part,for example,the appearance of pyrite often produces a hole at the surface.Stony appearance exists in both interior part and exterior part and affects the quality greatly;the existence of starry distribution will apparently affect the homogeneity.The component tremolite can also appear as stony appearance with its texture different remarkably from surrounding jades.Different sorts of minerals such as diopside and calcite can also display stony appearance.The existence of cracks is not always a bad thing,as bright-color may occur along the crack surface.The results achieved by the authors have some significance for identification,evaluation and design.Nevertheless,these relationships deserve further investigation.