在湘西北羊耳山煤矿区南部诸矿井内,煤层伪顶炭质页岩中分布有许多大小不一的球状体,当地煤矿工人称之为“龟石”。这些“龟石”是一种大型的钙质结核,其形态,个体大小以及分布与煤层分布和厚度变化有密切关系。由于这种钙质结核直接覆于煤层之上,对煤 Within the mines in the southern part of the Yangershan Coal Mine in western Hunan Province, there are many spheres of different sizes distributed in the pseudo-top carbonaceous shale of coal seams, which are called “turtle stones” by local coal miners. These “turtle stones” are large forms of calcareous nodules whose shape, size and distribution are closely related to the distribution and thickness of the coal seam. Because of this calcium nodules directly over the coal seam, on the coal