Located 80 km north of Seville, Spain, Aguablanca represents SW Europe’s only
known Ni sulfide deposit. Rio Narcea Gold Mines, Ltd. (Rio Narcea) acquired
Aguablanca from Atlantic Copper S.A. and Presur in July 2001 and completed a
bankable feasibility study in July of 2002. Construction of the mine began in mid-
2003 and commissioning commenced at the end of 2004. The open pit mine is expected
to achieve an annual production of 18 M lbs of Ni, 14 M lbs of Cu and 20,000 oz of
PGM (Platinum Group Metals) for a period of 10.5 years.
The open pit reserves of Aguablanca are 15.7 Mt at 0.66% Ni, 0.46% Cu and
0.47 g/t PGM with a strip ratio of 5.4:1, using a Ni price of $2.99/lb and a Cu price of
$0.73/lb. The ore will be processed through a sulfide flotation plant at a rate of 1.5 Mt
per year. Overall recoveries to a bulk concentrate are estimated at 82% for Ni, 85%
for Cu, and 75% for PGM and cobalt.
The Aguablanca deposit consists of disseminated to semi-massive magmatic sulfide
mineralization hosted by gabbro and gabbro-norite. The highest Ni and Cu
grades occur in a magmatic breccia that consists of fragments of ultramafic (pyroxenite
to gabbro-norite) rocks, skarn, hornfels, and marble in a mineralized matrix of
pyrrhotite, pentlandite, chalcopyrite and pyrite with minor marcasite and covellite.
The disseminated mineralization consists of interstitial sulfides within the silicates
(pyroxene, plagioclase) of a porphyritic gabbro. Magnetite is common and lesser
amounts of PGM and gold are also associated with the sulfide minerals. A system of
parallel, post mineral, N40E trending, strike slip faults dipping 75° to 80° to the SE
dismembers and laterally limits the mineralization.
The gabbroic stock that hosts the Aguablanca deposit is located along the northern
contact of the Santa Olalla Plutonic complex, a Variscan massif consisting principally
of quartz-diorite, granodiorite and monzogranite. The complex intrudes Upper
Precambrian-Middle Cambrian meta-pelites, marble and calc-silicates on the southeastern
flank of the northwest trending Olivenza-Monesterio antiform that extends
250 km across the Ossa Morena tectonic zone of the Iberian Peninsula.
The Aguablanca stock and the Santa Olalla plutonic complex are two of numerous
acid to mafic intrusives in the Ossa Morena Zone that reflect a complex tectonic
evolution. Multiple magmatic episodes related to Cadomian and Variscan orogenic
cycles with an intermediate anorogenic rifting phase have created a diverse metallogeny
with significant potential for the discovery of economic Ni-Cu sulfide and
IOCG deposits, and to establish the Ossa Morena Zone as one of the important mineral
producing belts of Western Europe.