The Zaruma Project is located in the central to north-central part of the Portovelo-Zaruma gold mining district in southern Ecuador, in which the total historic gold production from high grade quartz vein systems was estimated to be approximately 4 to 5 million ounces.
The hills of Zaruma and Portovelo have been mined for gold and silver for centuries. The Incas had been extracting gold and silver from the area with hydraulic mining of the oxidized parts of veins when Mercadillo, one of Pizarro´s force, followed the Rio Amarillo River upstream and encountered the Inca mine and founded the town of Zaruma in 1549. Exploitation of the Zaruma and Portovelo districts continued during the time of Spanish colonization until 1870 when an Ecuadorian-Chilean company was established.
In 1880, Grant Zaruma Company, registered in England, bought controlling shares of the Ecuadorian-Chilean mining company. Operational rights were immediately endorsed to Southern American Development Company (SADCO), an American company, which operated the mine from 1897 to 1950 by gaining control of the district’s main gold deposits in 1897. Exploration programs of SADCO commenced in 1896 and brought the mine into production at 108 tonnes per day in 1905. The mine was subsequently deepened to 13 levels located at an elevation of 270 metres above sea level and 800m below the uppermost workings. In the 53 years that followed, SADCO recovered some 3.5 million ounces of gold and 12 million ounces of silver from 7.6 million tonnes of ore at a cut-off grade of 14.4 g/t Au and 48.9 g/t Ag.
Lower levels of the Portovelo mine were flooded in 1944 and facing increasing costs, taxes and a complicated political situation, SADCO finally withdrew from the country in 1950 and the Ecuadorian government took over the mine. A state-owned company, CIMA, took over the mining operations in the area until 1980 and it is estimated to have produced a further 375,000 oz of gold between 1950 and 1965. In 1984, thousands of poverty-stricken miners invaded the old SADCO pits and small-scale and artisanal mining has continued in this area in specific locations. It is estimated that an additional 35,000 to 50,000 oz of gold has been produced each year since then by informal miners, small-scale operating mining societies and principally from the family-owned BIRA. Statistical information from the 1990s indicates that mining from the Zaruma and Portovelo areas could be some 3 million tonnes.
In the mid-1990s several foreign companies attempted to consolidate the area and carried out systematic exploration programs. In 1995, the Canadian-based TVX Gold Inc. reached agreements with most of the Zaruma area mining societies and informal miners and started with underground and surface mapping particularly within the Zaruma and Muluncay areas from March 1995 until February 1996. When TVX withdrew from Ecuador in 1998, all information was acquired by IAMGOLD. IAMGOLD continued with more extensive exploration programs including surface trenching, surface and underground sampling, surveying and diamond drilling. IAMGOLD significantly improved the Zaruma Gold Project area with legal consolidation of titles, adding valuable information to the project database, employing systematic geochemical data quality control and undertaking geological modelling.
In August, 2003 all the IAMGOLD properties were acquired by Core Gold's former management team. In October, 2003, the properties were transferred to Core Gold for reimbursement of transaction costs only. Core Gold also acquired the IAMGOLD data as part of its purchase of the concessions.
TOTAL MINERAL RESOURCES CONTAINED IN ZARUMA PROJECT
(as per Zaruma Technical Report linked below)
|Cabo de Hornos
- Mineral Resources that are not Mineral Reserves have not demonstrated economic viability.
- A cut-off grade of 2.06 g/t Au was used to derive the Mineral Resource estimate.