Abstract

History, production, and general geology of the Santa Barbara camp as known from published sources are briefly reviewed. A long known but previously unpublished spatial positioning of ore shoots in a district-scale dome is described, and comments on structural factors in ore pinchouts and ore quality are added.Ore pinchouts occur when the angle of intersection between a vein and bedding decreases to a critical angle of 23 degrees . Quality of primary ore may be related to any combination of factors such as angle of intersection between vein and bedding, irregularity of vein shape and coincident predominance of sulfide-ribboned breccia fragments, and the presence alone or together of either of two distinct types of ore mineralization--a lead-silver type and a deeper copper-gold-silver type.The Cabras and Bronces ore shoots are described. The bonanza grade and tonnage of these ore shoots are related to the irregularity of their shape and the superimposition of both the lead-silver and copper-gold-silver types.Depth-related decrease of lead-silver type mineralization may be partly offset by the appearance of copper-gold-silver type at depth, as in the Clarines vein, or with both types appearing in a split (Bronces) below the bottom of mining of a branch containing only one type (Tecolotes vein).

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