Jack slep Oct 21, 2016:

вмещающие породы is almost always "country rock(s)" not host rocks. Country rock is rock enclosing or traversed by a mineral deposit, e.g., a vein system, or by an igneous intrusion. Host rock is a body of rock serving as a host for other rocks or mineral deposits, e.g., a pluton containing xenoliths, or any rock in which ore deposits occur. Host is a rock or mineral older than rocks or minerals introduced into or formed within it. Both are wall rocks.

Vadim Khazin Oct 20, 2016:

This does not make sense, unless you put "вмещающиеся" instead of "вмещающие"