Exploration – Overview

Like the Cactus and Parks/Salyer deposits, MainSpring, the NE Extension and Gap Zone all extend over a portion of the large porphyry copper system that has been dismembered and displaced by Tertiary extensional faulting. Major host rocks at Cactus are Precambrian Oracle granite and Laramide monzonite and quartz monzonite porphyries.  The porphyries intruded the older rocks to form mixed and monolithic breccias that occur as large masses, poorly defined dike-like masses, and thin well-defined but discontinuous dikes. The mineralization is structurally complex with intense fracturing, faulting, and both pre-mineral and post-mineral brecciation. 

The long section below displays the horst and graben fault block geometries and mineralization interpretations from the Parks/Salyer deposit to the NE Extension. NE movement along the basement fault was accommodated by block rotation and the formation of NW trending normal faults resulting in the formation of horst and graben blocks. The existing Cactus West pit is displayed on the long section below.

Historic drilling by Asarco in the Gap Zone and NE Extension focused on near, or relatively near surface, enriched copper mineralization exploring for open pit resources. Rarely was deeper mineralization tested to its full extents or to the depth of the underlying Basement Fault. 

Drilling at MainSpring has confirmed the presence of shallow mineralization at a depth of 140 ft (43 m) from surface, consisting of oxide, enriched and primary mineralization. Bounding normal faults to the east and west create a shallow horst block that gently drops into the deeper high-grade Parks/Salyer deposit to the north through a series of north-dipping normal faults. Click here to view legacy drill assays from the MainSpring property as reported on January 25, 2025 in Tables 3 and 4.

The combined results of the recent ionic leach survey, and the 2020 SkyTEM survey, identify the Gap Zone directly west of the Cactus West open pit and east of the Tailings Facility as a high potential target for future drilling. Additionally, ASCU’s success demonstrating continuity of mineralization in the far NE of the property, indicates that additional drilling should be conducted between the known Cactus East deposit, and hole ECN-128. The zone to be explored contains a strike length of 2,952 ft (900 m). 

Ionic leach samples were collected on a 328 ft (100 m) grid (with local infill to 164 ft (50m) along the entire length of the Cactus Project trend from Parks/Salyer, in the SW corner, through to the NE Extension zone, in the NE corner of the Project. As expected, copper values were elevated over the Parks/Salyer mineral resource area, and also at the GAP area between the Cactus West open pit and Parks/Salyer (FIGURE 3). Interpretation of the ionic leach results at Parks/Salyer (relative to underlying mineralization in drilling) suggests that stronger levels of metals are associated with thicker intervals of leached rock overlying the resource as opposed to areas where Primary or Enriched mineralization is exposed at the top of bedrock. The NE Extension area and ECN-128 demonstrate a similar relationship. 

The NE Extension exploration hole was collared approximately 40.0 ft (12.2 m) from ASARCO’s hole S-68 and intersected mostly continuous mineralization from 996.7 ft to 1987.4 ft (in vertical depth). The intersect includes 118.1 ft (36.0 m) of 0.94% Cu TSol oxide mineralization from 996.7 ft (303.8 m). ECN-128 was designed to verify the oxide/enriched mineralization relationships previously drilled by S-68 (included in the drill assay highlights table below) and to explore the previously underexplored primary mineralization by drilling through the full bedrock profile to the Basement Fault.