Section 1: Location and Background
The El Pilar porphyry copper system is located in eastern Cuba, near the town of Moa. It is one of the most significant copper-depositing systems in the Caribbean region. The area is currently under exploration and development by Canadian mining company Sherritt International.
Section 2: Geological Context
The El Pilar system lies within the Mesozoic-aged magmatic arc terrain, which has a significant volcanic and intrusive history. The complex geological setting comprises various rock types, which include pyroxene andesite, granite porphyries, and granodiorite, overlaying sedimentary rocks of the Upper Jurassic to Lower Cretaceous age. The varying nature of the substrate partially explains the diverse mineralisation pattern observed in this copper system.
Section 3: Ore Mineralogy
The El Pilar deposit is a classic example of a porphyry copper system, characterized by copper mineralisation predominately as chalcopyrite, with minor occurrences of bornite and molybdenite. The disseminated nature of the ore reduces the ore grade but significantly increases the volume, presenting opportunities for large scale, open-pit mining operations.
Section 4: Geochemical Characteristics
El Pilar porphyry copper system exhibits strong hydrothermal alteration. The metals are leached from the rocks and re-precipitated as oxide and sulphide mineral assemblages in the veins and breccias. Copper mineralisation is spatially related to the intrusive centres and exhibits a zonal pattern, with the highest grades concentrated centrally and decreasing outwardly.
Section 5: Geophysical Features
Geophysical investigations, including magnetometry and Induced Polarization (IP) surveys, have been very useful in delineating the spatial distribution of mineralisation and the subsurface geology. A strong magnetic signature associated with the intrusives and the high chargeability linked to sulphide mineralisation are critical pointers in the exploration strategy.
Section 6: Exploration and Mining Potential
The El Pilar porphyry copper system, with its significant copper resource potential, is a valuable asset to Cuba. The deposit, although not in current production, appears ripe for exploitation. The mineralisation occurs near the surface which, coupled with the relatively disseminated nature of the copper minerals, suggests that this deposit could be mined economically using open-pit techniques.
Section 7: Environmental Consideration and Mitigation
Given the increasing global attention to responsible mining,