寿山石是我国国石候选石之一, 也是四大图章石之首。 寿山石中黑田为黑色田黄石, 是田黄中的特殊品种, 产于寿山溪两旁的田地中。 母源区坑头占的位置产有黑色坑头石。 本文将黑田与母源区的黑色坑头石（坑头黑）进行对比研究, 采用X射线粉晶衍射（XRD）、 红外吸收光谱（IR）、 激光剥蚀等离子质谱仪（LA-ICP-MS）和扫描电镜（SEM）对它们的矿物成分、 红外吸收峰特征、 颜色成因以及矿物的微区形貌特征进行对比研究。 测试结果显示, 黑田与坑头黑的矿物成分不同, 红外光谱和X射线粉晶衍射分析表明坑头黑以地开石为主; 另外, X射线粉晶衍射分析表明坑头黑中可含有杂质矿物如叶蜡石、 伊利石、 黄铁矿和石英。 而红外光谱和X射线粉晶衍射分析表明黑田的主要成分为地开石或者珍珠陶石; 另外, X射线粉晶衍射分析表明黑田中含有少量的硫磷铝锶矿和镁硫铁矿。 黑田与坑头黑的矿物微形貌也存在差异, 黑田矿物晶粒大小不一致、 片状晶体颗粒边缘圆化, 说明黑田中矿物晶体曾遭受过水岩反应的溶蚀改造作用。 而坑头黑中地开石结晶程度良好, 晶粒呈片状, 边棱尖锐, 晶体颗粒大小较为一致, 说明坑头黑为原生矿。 根据LA-ICP-MS微量化学成分分析测试, 初步认为黑田与坑头黑的黑色皆与Fe元素致色有关, 该结论有待进一步测试研究。

Shoushan Stone is one of the national stones of our country which is also the most famous stone of the four outstanding seal stones in China. As to Shoushan stones, black Tianhuang stone is a kind of black colored stone. It is one of the most special species in Tianhuang stones which comes from fields beside the Shoushan Brook. The black Kengtou stone comes from Kengtou Zhan, its original place. In this study, black Tianhuang stone is studied and compared with black Kengtou stone by using X-ray powder diffraction spectrometer (XRD), infrared spectrometer (IR), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and scanning electron microscopy (SEM) in order to analyze the mineral composition, characteristic of infrared spectra, color genesis, and characteristic of micro- morphology of these stones. The results of the study indicate that the mineral compositions are different between these stones. The analysis of IR and XRD studies indicate that the black Kengtou stone is mainly composed of dickite. On the other hand, XRD analysis indicates that it can contain a small amount of pyrophyllite, illite, pyrite, and quartz. However, the analysis of IR and XRD studies indicate that black Tianhuang stone is mainly composed of dickite or nacrite. On the other hand, XRD analysis indicates that the minor mineral composition in the black Kengtou stone can be svanbergite and tochilinite. Their characteristics of micro-morphology of black Tianhuang stone and black Kengtou stone are also different. The crystal size of dickite in black Tianhuang stone is inconformity, and the margin of lamellae crystals is smoothed. It indicates that such kind of stone had undergone corrosion effect due to water-rock reaction. On the other hand, the black Kengtou stone are well crystalized. The lamellae has sharp margin, and the size of the lamellae is relatively uniform. It indicates that the black Kengtou stone is original ore. According to the trace chemical composition analysis of LA-ICP-MS, it preliminary suggests that black color of both black Tianhuang and Kengtou stones have relationship with Fe element. The final conclusion of color genesis needs more experiments to prove.