容矿围岩对于成矿溶液的成分,因而也就对矿石的成分必然要产生影响.但由于成矿作用如同多数地质过程一样,是一个随机-概率过程,所以围岩成分对内生矿化赋存影响的一般规律,只能通过掌握尽可能完整的数据来表征.也就是说,某一种围岩对于一定类型的矿化是有利还是不利,应当理解为一种主导的趋势,而其中必有一些例外.阐明外贝加尔地区的这种主导趋势和其中的例外情况,即为本文之目的. Surrounding rocks of ore-bearing rocks are inevitably affected by the composition of ore-forming solution, but as the mineralization, like most geological processes, is a stochastic-probability process, The general law of the effects of occurrence can only be characterized by the mastery of as complete data as possible, that is, whether a certain type of rock is good or bad for a certain type of mineralization should be understood as a dominant trend, There are some exceptions to be made, and it is for the purpose of this article to clarify this dominant trend and its exceptions in the region of Outer Baikal.