Basing on the study results and applying theoretical models, the paper analyzes and explains the characteristics of metasomatism, as well as its relation to minerals, especially precious metal group (Au-Ag) with the case of western area of Qu¶ng TrÞ in the North Central ViÖt Nam. The following conlusions can be drawn from this study.

1. The North Central ViÖt Nam in general, and western area Qu¶ng TrÞ in particular, has a large potential of gold mineralization. This mineralization belongs to plutonic and volcanic hydrothermal genetic types, which is related to the tectono-magmatic stages of late Paleozoic - early Mesozoic and late Mesozoic age.

2. There are the successive – paragenetic relation between the metasomatic activities and the gold mineralization of the study area. Basically, the metasomatic process is an important activity of magmatic-hydrothemal metasomatic-ore deposition process. The metasomatic formations are direct signs for prospecting the primary gold ore, and they are just concretized evidences of magmatic premises.