The La Demajagua gold/silver deposit incorporates the Delita deposit which was discovered around 1900 but received only cursory attention until the 1920s when a North American company acquired the concession. Production was minimal until after World War ll.
In the period 1947 – 1950, approximately 60,000 t of ore were mined underground. As mining progressed in depth, the material changed from shallow, oxide-zone material, to sulphidic arsenic mineralization. Reports suggest that 60,000 t were mined at a recovered grade of 14 g/t gold. A 40 tpd beneficiation plant was constructed to drive off arsenic and sulphur, and concentrates were shipped offshore to a smelter for direct refining. The property was abandoned in 1958 when the concentrator ceased operating.
During the 1970s and 1980s, regional exploration, mapping and geophysical surveys were conducted, and between 1977 and 1980, trenching and drilling were conducted on the Delita property. This work expanded resources considerably.
Following a 1980 study, a new shaft was sunk and a flotation and gravity process plant constructed, with approximately 80,000 t of ore processed through the plant. High recoveries of gold and silver, reporting to flotation and gravity concentrates, were achieved in the plant, which had a nominal 60-80 tpd capacity. However, the inability to process the refractory concentrates prevented operations from being expanded to full scale production.
Concentrate product was reported as 30g/t to 60g/t Au, 15% to 20% As and 20% to 30% S.