.
Location: 72 km SW from Medellin, Colombia
Carrera 43 N 1A SUR-69 Oficina 701 EdificioMedellínColombia
Stay on top of the latest gold discoveries. Examine the latest updates on drilling outcomes spanning various commodities.
Mining scale, mining and mill throughput capaciites.Full profiles of select mines and projects.
Shaft depth, mining scale, backfill type and mill throughput data.Full profiles of select mines and projects.
Equipment type, model, size and quantity.Full profiles of select mines and projects.
Camp size, mine location and contacts.Full profiles of select mines and projects.
- subscription is required.
The El Roble massive sulfide mineralization is classified as the ‘mafic-type volcanogenic massive sulphide type’. Atico geologists and other workers use four major rock classifications to described the geology of El Roble license areas. The lowest unit is a submarine mafic volcanic unit up to several kilometers thick. Whole rock (NaO, K2O, MgO, FeO) analyses reported by Ortiz et al. (1990) place the basalt flows in the tholeiitic field. The mafic volcanic unit is overlain by a “black chert unit” up to 30 m thick and turn these grades upwards into a pelagic sedimentary unit, locally termed the “grey chert” up to 120 m thick. The entire package is topped by a sandstone-mudstone, turbidite unit several kilometers thick. The massive sulfide deposits are hosted in the black chert and grey chert units always occurring within meters of the uppermost mafic volcanic contact. The succession of basalt flows, black to grey chert and overlying pelagic sedimentary rocks and sandstone-shale turbidites sequence has been intruded by andesite and latite dikes which post date and disrupt the massive sulfide mineralization. Mineralization The El Roble deposit consists a series of massive sulfide lenses, separated by faulting and are the dismembered fragments of once coherent, single, massive sulphide body. The mineral deposit that comprises the El Roble Project consists of mafic-type volcanogenic massive sulfide (VMS) mineralization for which there are numerous examples in the world. The host rocks for the VMS mineralization present on the MINER El Roble mineral concessions consist of basalt flows, black to grey chert and overlying deep-water sedimentary rocks, and sandstone. The deposition of the VMS mineralization is syngenetic with the black chert, which generally forms both the hanging wall and footwall “host” to the mineralization. The portion of the El Roble deposit currently being mined by MINER has been overturned by folding such that it now dips steeply to the east. Based on the drill hole data provided by MINER as of the effective date of this amended Technical Report, the dimensions of the deposit currently are 325 meters along strike by ±600 meters deep and up to 45 meters in thickness. Continuity of the mineralization is locally disrupted by Tertiary andesite and latite dikes up to 10 meters in width that intrude both the VMS mineralization and the host rocks. Strands of one of the major regional northwest-striking faults have resulted in conjugate N-S, E-W NW-SE faults offset the mineralization particularly below the 2100 level of the mine. The massive sulphide mineralisation is fine-grained, with only locally evident internal structure or banding, consisting predominantly of fine-grained pyrite and chalcopyrite. Pyrite occurs as euhedral and subhedral grains that vary from 0.04 to 0.01 millimeters in diameter. Colloform pyrite textures and crushed pyrite grains are also common. Chalcopyrite typically fills spaces between pyrite grains, along with minor pyrrhotite and sphalerite; no other sulphide minerals have been identified. Gold occurs as electrum in 10- to 100-micron irregular grains in the spaces between pyrite grains. Minor silver is also present, presumably as a component of the electrum. Gangue minerals include quartz and chlorite along with lesser calcite, dolomite and minor hematite and magnetite.
