1956年秋,笔者在河北省北部密云、怀柔一带收集毕业论文资料时,曾在怀柔县北约20公里之河防口村三岔附近发现一种绿色片岩,该片岩出露于花岗岩与石灰岩之间。经野外观察及室内研究,认为原是一种基性火成岩——辉绿岩,经后期花岗闪长岩侵入蚀变——青盘岩化的结果。其形成环境,较比特殊,兹将 In the autumn of 1956, in the collection of dissertation information in Miyun and Huairou areas in northern Hebei Province, the author found a green schist near the Sancha, Fangkoukou village, about 20 kilometers north of Huairou County, which was exposed between granite and limestone. After field observation and indoor research, it is considered that it was originally a basic igneous-diabase, and was intrusive alteration of later granodiorite-the result of petrified rock formation. The formation of the environment, more special, hereby will