SOME MINERAL DEPOSITS SURVEYED BY JOSÉ ARCE GEOFÍSICOS S.R.L.

Cerro Verde-Santa Rosa (June-September 1971). First time that Induced Polarization soundings were applied in Perú, after Newmont's survey in Cuajone (1951). The decision to apply this technique was taken after comparison with IP profiles in the field. Definition of mineralization limits and location of the first two drill holes that went deep into the Santa Rosa sulphides. Important.

Raura (September 1971). IP profiles led to the discovery of the Catuva extension. Key solution when Catuva was considered to be completely mined-out.

Coronguillo-El Chorro (December 1971-May/September 1996). Geophysical discovery of an anomalous area with more than 12 km2 of area. Induced Polarization soundings and ground magnetometer profiles were used. Probable porphyry system.

Tintaya (December 1971-January 1972). Geophysical discovery of the sulphide bodies "Inflexión Norte" and "Chabuca Este". Each of them resulted in over 30 Mt of ore reserves. Important, because decisions were taken during fieldwork to perform isolated reconnaissance IP soundings. Very precise computation of depth to sulphides.

Quellaveco (October 1972-March 1999). Definition of mineralization limits in Quellaveco and Charaque, with the aid of IP soundings. In 1999, a detailed survey between both areas, also helped defining areas without sulphides, to be used for mine operation sites.

Cerro Lindo (June 1973). Preliminary geophysical anomalies, with IP profiles.
Chalcobamba (June 1974). Detailes maps of the deposit with IP profiles. Reconnaissance work at Ferrobamba (extended in 1995, with IP soundings), Charcas and Sulfobamba. Ferrobamba had a better response than Chalcobamba and great importance was assigned to Sulfobamba (IP soundings).

Antamina (July 1974-July 1995). IP exploration previous to the drilling campaign of E.M.E. Antamina SRL. In 1995, before international bidding of the property, ground magnetometer line-survey, including over the Antamina lake.
Antapacay (September 1974). Induced Polarization for C.M. Atalaya. In 1999-2000 BHP Tintaya found the porphyry-type deposit with our chargeability anomalies. Discovery, 25 years after the survey.

Pashpap (December 1974). Successful survey of the Huacacuy area with IP soundings where another company had no geophysical results in 1969. Special, for being a survey performed at two different times.

Bongará (November 1975). Electrical profiles (IP) and electromagnetics to determine their applicability to stratified zinc deposits with few sulphides. High precision measurements in weak anomalies.

El Indio-Tambo (April 1976 & March 1977). Large-scale surveys of the area that in 1981 would become the main gold deposit in Chile. Discrimination of silicified masses and enargite. IP/RES/SP+EM profiles.

Cerro Corona (September 1979). Detail self-potential, resistivity and chargeability contour maps. Clear definition of the deposit's limits. The SP anomaly delineated perfectly the deposit. IP/RE/SP profiles.

Tambo Grande (October 1979). Very precise correlation between resistivity anomaly and the mineralized body, with IP/RE profiles. Depths to the target computed with vertical soundings, and were later confirmed. Very precise calculations of depth to the mineralized body.

Pascua (Nevada, February 1980). General SP-RE-IP survey of the gold deposit currently being mined.

Santos (Candelaria, May 1980). Successful correlation of geophysical anomalies (IP/RE profiles) with ore bodies in Copiapó, permitted interpreting that these were marginal and part of a large porphyry-type system, currently being mined. This survey allowed the property owners to sell their ore bodies in highly favorable terms.

Carolina (August 1982). Chargeability contour maps led to the discovery of large sulphide bodies in Arpón (Hualgáyoc). Important for its exploratory consequences. IP/RE/SP profiles.

Poderosa (March 1987). After several months of drilling and studies to try to intercept the faulted "Mercedes" vein, our geophysical survey located the missing body with IP/RE profiles, and determined its depth with IP soundings. Important to precisely locate the continuation of the vein.

Atocongo (January 1989). In order to measure the vertical reach of the puzzolan quarry, we ran IP/RE soundings. The basement showed a chargeability anomaly and the first drill hole confirmed a mineralized body with high copper values. Typical case of a mineral discovery when studying a geological problem.

Yanacocha (April 1993). While studying physical parameters of the Carachugo orebody prior to the start of mine operations, we discovered an SP anomaly of 6100mV perfectly correlating with the location of the gold-bearing horizon, and we interpreted under it the existence of a possible copper porphyry orebody (chargeability soundings).

Cuajone (November 1993-January 1994). Comprehensive survey with IP/RE sounding stations. Geophysical anomalies confirmed with extensive drilling, which led to great additional reserves. Excellent correlation between geology and our geophysics.

Cerro Negro (June 1995). We surveyed this area, located southwest of Cerro Verde. It was previously explored in 1954 with an IP survey by the Newmont group. We defined the chargeable minerals location, the location of the highly resistive breccias, as well as the fault which divides this volcanic neck in two parts. Clear correlation with field geology. IP/RE soundings.

Lara (February 1997). Isolated IP sounding stations located, taking decisions as the survey progressed, and following trends with better geophysical responses, allowed delineation of an anomalous target with two separate centers. The geological map prepared a month after our survey showed a significant correlation with the geophysics. Very flexible field procedure, without previous topographic surveying and no geological control. Copper porphyry.

Los Chancas (May & November 1997). The presence of two clear chargeability-resistivity anomalies obtained with IP/RE soundings, along with ground total field magnetometry, allowed SPCC to confirm the existence of a new deposit, still under study. The May survey was done without any topographic control, like the Lara case; in the September campaign, detail was improved and the survey area was extended. Copper-Molybdenum porphyry system with skarn-type masses.