The area of the Minera Florida Mine is underlain by upper cretaceous volcanic and intrusive rocks. The volcanic rocks comprise porphyritic andesite, brecciated andesite, lithic and crystal tuff, and brecciated tuff. The bulk of these rocks are also affected by a sequence of hydrothermal alteration. The intrusive rocks comprise mainly granodiorites and monzodiorites.
Gold mineralization in the Minera Florida Mine area occurs as native gold and electrum associated with sulphide minerals, such as pyrite, chalcopyrite, sphalerite and galena, as well as magnetite. Mineralization is commonly associated with hydrothermal alteration including quartz, adularia, epidote, chlorite, and actinolite. Quartz occurs in four types; as grey siliceous zones, green quartz, translucent quartz, and white quartz. Some veins exhibit metal zoning, with a zinc-rich silver-rich zone in the upper part of the vein, a goldrich zone in the central part, and a zinc-rich zone in the lower part of the vein.
In general, mineralized structures include an inner quartz vein (core) consisting of material exhibiting quartz flooding or massive quartz, surrounded by stockwork of quartz veinlets and/or hydrothermal breccia, both of which are mineralized. Gold mineralization in the Minera Florida Mine area has been identified in four types of rocks, in places adjacent to each other, as follows: (1) silicified crystal tuff; (2) lithic to crystal tuff; (3) brecciated tuff; and (4) porphyritic ........
