Gold mineralization at Segovia occurs in mesothermal quartz-sulfide veins hosted by a batholith. They have been classified as “Oxidized Pluton-Related Gold Deposits” (Sillitoe, 2008), are thought to have formed after the cooling of the batholith and may have a genetic relationship with the batholith as well as with the regional stress regime related to the Otú fault.

Gold mineralization at Segovia occurs in mesothermal quartz-sulfidic veins hosted by diorite to granodiorite rocks of the Segovia Batholith. The well-known, partially exploited veins dip at approximately 30° to the east or north-east. There are also a number of steeply dipping shear-zones hosting quartz veins with a N40W trend in the western part of the concession, termed the Las Verticales Veins System.

In general, the veins are formed of quartz with minor calcite and coarse-grained sulfides comprising pyrite, galena and sphalerite, and typically show a close spatial relationship with lamprophyre to adakite dykes. Gold and electrum occur as fine grains (<20 microns) and visible gold is generally common in the high-grade shoot sectors of the mines. Native silver has been reported. The wallrock alteration to the veins affects the basalt dykes and the granodiorite in a narrow zone a few meters wide with potassic (biotite), argillic (illite) and propylitic alteration most commonly encountered along with selective mineral replacement by chlorite, epidote, pyrite and calcite.

Gold ........

The Segovia operations are located in a historic mining district that has been mined for over 150 years. The majority of the mineralization has a dip of approximately 35°. The current mining methods used at the Segovia operations include room and pillar mining as well as cut and fill. Material is typically removed from the mine through use of an apique hoist system (angled hoisting system which follows the dip of the vein structure).

Current Room and Pillar Mining Method
Room and pillar mining consist of a primary and secondary phase. The primary phase mines a traditional room and pillar layout to a stated extraction ratio and the secondary phase extracts additional material from pillars.

Primary Mining
Primary mining applies a conventional room and pillar technique using manual mining methods. The panels are accessed from the overlying and underlying haulage levels as well as from down-dip development that breaks up the panels into discrete mining blocks. A loading chute from which the mined rock can be loaded into the materials handling system is constructed within the lower haulage level access. Sublevels are then developed horizontally along strike. A slusher is an air powered or electric scraper that is used to pull muck from the face back to the loading chute. Rooms between the sublevels are mined creating the room and pillar layout. The sublevels have an ore chute either at the end or middle of the panels. The layouts follow the typic ........

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