Unigold has been active on the Neita Concession since 2002 and has been steadily moving the project up the value chain. In 2020, the Company revised the Mineral Resource Estimate for the Candelones area and in 2021 released a Preliminary Economic Assessment for the oxide mineralization at Candelones. Current resources stand at 1.15 million ounces of Measured and Indicated material, and a further 1.1 million ounces of inferred mineralization (please see the Micon 2020 MRE Report for more information). The deposits are open to depth and new high-grade veins are being discovered along-strike.
The Company is completing a feasibility study on the oxide portion of the deposits and costing a heap leach operation that will produce between 30,000 and 40,000 ounces per year for a 3 to 4 year period. The oxide project provides an opportunity for Unigold to assemble permits, supply lines and a trained workforce prior to developing the much larger sulphide resource at Candelones. The delivery of this project will be the Dominican Republic’s second gold mine after Pueblo Viejo and will signal the start of a new industry in the Caribbean nation.
The Company’s Neita Concession encompasses 21,031 Ha of the Tireo Formation, a thick sequence of intermediate volcanic and volcanoclastic rocks produced by island arc volcanism that are highly prospective for:
- Porphyry Cu and Cu-Au deposits;
- High to low sulphidation Au and Au-Ag epithermal deposits; and
- Volcanogenic Hosted Massive Sulphide (“VHMS”) Au-Ag-Cu-Pb-Zn deposits.
Project to date investment totals CAD$ 51.0 M. Completed work includes:
- Soil geochemistry of the entire concession (32,000 samples) that has highlighted twenty one (21) prospective targets;
- 11,000 surface rock geochemistry samples confirming all identified soil anomalies;
- 32,000 meters of surface trenching, predominantly at the Candelones Main and Connector deposits;
- 135,000 meters of resource definition drilling at the Candelones Main, Connector and Extension deposits;
- 23,000 meters of reconnaissance exploration drilling at 12 additional targets.
The Company has trained and employs a Dominican labour force and maintains a 98.5% local (25 km radius) hire rate.
Mineral resource estimates and NI43-101 reports have been completed in 2007, 2013, 2015 and 2021 (see NI43-101 Technical Reports tab here). Drilling prior to 2015 concentrated on a large area of disseminated suphides that averaged about 1.5 g/t utilizing wide-spaced drilling on 100 meter centers. In Q4, 2015, the Company initiated a diamond drill program to increase the geological confidence of the inferred mineral resource by targeting high grade intercepts identified in the initial 100 meter spaced drill pattern. The first hole in this program, LP15-93, a 50 meter step out hole from LP17 (6.0 meters averaging 6.05 g/t Au; 0.8% Cu), intersected pyrite rich massive sulphide mineralization returning 15.7 meters at 7.45 g/t Au; 1.1% Cu.
Drilling has since extended high grade mineralization at three distinct target areas. The results to date suggest that the Candelones deposits are a result of multiple phases with a minimum of three separate mineralization events.
An initial, VHMS event deposited Au, Ag, Zn, Pb and Cu as stratiform mineralization within a dacite breccia that typically extends 20 to 100 from the hanging wall andesite volcanics. This was followed by an initial epithermal gold copper event which introduced mineralization along conjugate fault systems formed during the development of a island arc system above a subducting oceanic plate. A second epithermal event, interpreted to be largely Au, Zn and Ag rich, was emplaced along the same reactivated fault systems. Finally, late stage intermediate to mafic dikes intruded these same fault systems which remobilized mineralization along the dike margins with a significant increase in Au grade.
Select results from the Company’s drill program targeting the high grade mineralization include:
Table 1.0 – Candelones Sulphide Drilling - Summary of Significant Results
|Target||Hole (#)||From(m)||To (m)||Interval (m)1||Au (g/t)||Ag (g/t)||Cu (%)||Zn (%)|
The accompanying longitudinal section demonstrates the sub-vertical continuity of the high grade systems, all of which remain open at depth. For a 3-D model, please refer to our Vrify.com project links.
The three high grade targets tested to date all lie within the Candelones Extension footprint of the 850 Ha Candelones Project area, representing less than 4% of the total Neita Concession area. Exploration at the remaining 18 targets highlighted by the soil geochemistry is minimal. As a result, the Company believes that there is significant potential for additional discoveries outside the Candelones Project area.
In 2019, the Company targeted the at surface oxide resource at Candelones Main and Candelones Connector identified as part of the 2013 mineral resource estimate. The objective was to increase the geological confidence of the 2012 mineral resource and evaluate the metallurgical response of the oxide resource. Metallurgical testing in 2020 confirms that the oxide mineralization is amenable to direct cyanidation with recoveries in excess of 90% after 72 hours in standard column tests. Additional metallurgical testing has shown that this oxide material is amenable to Run-of-Mine heap leaching. A PEA was completed in 2021 which showed good economics with a rapid payback. Feasibility level work is underway with an expected completion of Q3 2022.
2021 Candelones Oxide PEA Technical Report
The island of Hispaniola is part of the Greater Antilles volcanic arc extending from Hispaniola through Cuba. The arc is a product of subduction of the North America plate below the migrating Caribbean plate. Volcanism related to the subduction zone emplaced of a series northwest trending litho-structural domains, three of which, the Tireo, Los Ranchos and Maimon Formations offer demonstrated potential to host economic gold and copper mineralization. Barrick’s flagship Pueblo Veijo Project (22 M oz Au resource) located within the Lower Cretaceous aged Los Ranchos Formation. The younger Tireo Formation hosts known gold and copper gold mineralization at Candelones (1.1 M oz indicated and 1.1 M oz inferred resource), Goldquest’s Romero discovery (1.1 M oz Au equivalent Probable Reserve) and Newmont’s La Miel project located 5 kms to the W in Haiti.
Regional Geology of Hispaniola
“Geologic Map of Hispaniola, Edited from Draper, Lewis and Gutierrez, 1995”
Local Geology, Structure and Mineralization
The Neita Concession is comprised almost exclusively of intermediate volcanic and volcanoclastic rocks of the Upper Cretaceous aged Tireo Formation, intruded by Upper Cretaceous to Eocene aged felsic to ultramafic intrusive rocks. The main structural fabric trends northwest, consistent with the dominant structural trend of the island. The southern boundary of the concession is marked by an east-west trending composite thrust fault, interpreted to be a splay off the main northwest trending San Jose – Restauracion thrust. The composite thrust faults parallel the main east-west splay creating a stacked sequence of andesitic and dacitic volcanic and volcaniclastic rocks.
The Company believes that at least three mineralizing events have formed the Candelones deposits. The initial phase of mineralization introduced low tenor VHMS mineralization (Au, Ag, Cu and Zn) within a brecciated dacite tuff extending from the overlying andesite for 20 to 100 meters. Gold, silver, zinc, lead and copper grades typically decrease as the distance from the andesite-dacite contact increases. Gold grades typically range from 0.10 to 2.00 g/t Au with minor associated silver, copper and zinc mineralization. The mineralization is interpreted to be a result of intermediate volcanism in a shallow, back arc environment.
In 2016, the Company intersected what it interprets to be higher grade, epithermal style mineralization along north-northwest and east-northeast faults zones. This mineralization offers significantly higher grade gold, silver and copper grades relative the the stratabound, VHMS type mineralization originally discovered.
Metallurgical testing in 2020 indicates that the later, epithermal mineralization offers enhanced metallurgical recoveries relative to the lower grade VHMS type mineralization. Gold recoveries of up to 88% were obtained in standard bottle roll leaching of floatation concentrate from the late epithermal mineralization.
The epithermal mineralization occurs within the same dacite breccia host rock but is discordant to stratigraphy with a sub vertical dip. The high grade lenses lie within the 100 meter stratabound mineralization and trends in an east-northeast direction, roughly parallel to the andesite-dacite contact. Within that east-northeast corridor, high grade lenses strike to the northeast or west-northwest, coincident with interpreted, sub vertical normal faulting. This produces an en-echelon series of high grade lenses that repeat throughout the trend.