Lake City Mining District, Hinsdale County, Colorado, USAi

Regional Level Types
Lake City Mining District	Mining District
Hinsdale County	County
Colorado	State
USA	Country

The lodes of the Lake City area are fissure veins. In the ordinary understanding of the term a fissure vein is a crack or crevice in the rock filled with later-introduced vein material. The Lake City lodes are only in part of this type. They have also been formed largely by replacement and exhibit all stages of the transition from a simple filled fissure, whose walls have been comparatively little affected by vein-forming solutions, to a zone of sheeting and brecciation where most of the mass of vein material has been produced by the alteration of the inclosing rock. Both types of mineralization are common in the same lode, one prevailing in one part, the other in another. In the Golden Wonder lode in Deadman Gulch the fractures are ill defined and the replacement has been extensive and irregular. This is perhaps the one deposit in the Lake City district that may be termed a characteristic replacement as distinguished from a fissure vein.