The Josemaría project is located in the San Juan Province of Argentina. Access to Josemaria is by major provincial highways and gravel roads from the city of San Juan, Argentina. San Juan is a major mining centre that supports a wide variety of mining service companies.
The climate in the project area is dry to arid and the temperatures are moderate to cold. Annual precipitation is about 250 mm. Exploration fieldwork is generally carried out from mid-October to early May. It is anticipated that mining operations would be conducted year-round, as at other mines operating in this environment.
Josemaria is a copper-gold (Cu-Au) porphyry system.
The copper-gold mineralization at Josemaria is mostly hosted by a Miocene porphyry system which forms an elongated body with minimum dimensions of 800 to 900 m north-south, 600 to 700 m east-west and 600 to 700 m vertically. The porphyry has been dated at approximately 24.7 Ma. The deposit is centered on a composite porphyry stock, which intrudes rhyolitic volcanic and tonalitic plutonic rocks of Permo-Triassic age. The earlier, more intensely quartz- ± magnetite-veined porphyry phases and nearby wall rocks display a telescoped sequence of alteration-mineralization zones, from shallow advanced argillic (mainly quartz-pyrophyllite) and underlying sericitic to deeper chlorite-sericite and remnant potassic; all of which are mineralized. The outermost parts of the copper-gold-zone are overlapped by a pronounced molybdenum-bearing zone.
The deposit was partially exposed by erosion, and then covered by post-mineral sedimentary and volcanic rocks. A north-trending, post-mineral fault zone has localized an economically important zone of high-grade copper mineralization hosted in supergene chalcocite enrichment in the northern part of the deposit.
The Josemaria deposit remains open to the south, beneath a thickening cover of post-mineral volcanic rocks, and also at depth.
A detailed description of the Josemaria deposit geology was published in the May 2019 edition of Economic Geology and can be accessed here.
Josemaria is a grass roots discovery made by Josemaria Resources Inc. (formerly NGEx Resources Inc., “NGEx”) during the initial drilling campaign in 2004. The first hole drilled encountered 280 metres grading 0.61% copper and 0.51 g/t gold, clearly indicating that a significant copper-gold deposit had been found.
Work programs conducted at Josemaria include geological mapping; soil, rock-chip, and talus sampling; a number of geophysical surveys including induced polarization (IP)–resistivity, magnetometer, and Mount Isa Mine’s Distributed Acquisition System methodology (MIMDAS) surveys; reverse circulation (RC) and core drilling, and Mineral Resource estimation. A number of environmental baseline studies have also been undertaken.
Eleven drilling campaigns have been carried out at the Josemaria deposit, from 2003 to 2020. Drilling at the Josemaria deposit to date totals 76,206 m in 190 drill holes, of which 48 holes (17,535 m) are RC holes, and 142 holes (58,671 m) are core holes.