大同煤田石炭−二叠系煤层中广泛分布有印支期和燕山期火成岩，使煤层发生接触变质作用。以往的研究表明塔山井田5222巷煤中微量元素Sr异常富集，接触变质煤和正常煤中Sr含量最大值分别为 3 067 μg/g和 2 729 μg/g，平均含量为 1 165 μg/g，是世界煤中Sr平均含量的10.6倍，但其赋存特征尚不清楚。通过对塔山井田5222巷煤和辉绿岩岩墙进行系统采样，综合运用电感耦合等离子体质谱（ICP-MS）、X射线荧光光谱（XRF）、带能谱的扫描电子显微镜（SEM-EDS）对样品进行Sr元素和主量元素含量测定及矿物学分析，结合元素相关性分析和逐级化学提取等方法，研究了煤中Sr的赋存状态。煤中Sr与P₂O₅的显著相关性和逐级化学提取试验得出，Sr可能主要与含磷矿物（磷灰石）和硅酸盐矿物（黏土）结合；扫描电镜分析得出这2类矿物紧密交互共生，磷灰石的种类包括呈六方柱形的氟磷灰石和嵌入在黏土矿物中呈细小分散粒状的羟基磷灰石。

Datong Coalfield was intruded by igneous intrusions in both the Indosinian (Late Permian to the end of the Triassic) and the Yanshan (Late Jurassic to the Early Cretaceous) periods, which caused contact metamorphism of the coal seam. Previous studies have shown that Sr is significantly enriched in coal from the 5222 tunnel of the Tashan coal mine. The maximum concentration of Sr in thermally-altered and unaffected coal is 3067 μg/g and 2729 μg/g respectively, and the average concentration of Sr is 1165 μg/g, which is 10.6times of the world average level in hard coal. However, the modes of occurrence of Sr in the Tashan coal still remain unclear. Samples in the 5222 tunnel including coal and intrusive rock were systematically collected. Inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence spectrometry (XRF) were applied to elucidate Sr concentration variations in the sample; correlation analysis, scanning electron microscope with energy spectrum (SEM-EDS), and sequential chemical extraction procedure (SCEP) were carried out to reveal the occurrence modes of Sr, as well as the characteristics of Sr-bearing minerals. The results demonstrated that Sr exhibits a strong correlation with P₂O₅ in coal; Sr mainly occurs in phosphate (apatite) and clay minerals that are intimately associated; apatite was distinguished as fluorapatite in the shape of hexagonal columns and hydroxyapatite in the shape of fine scattered particles embedded in the clay minerals.