Great Plains Metals Corp. Announces Discovery of "Pencil Porphyry" at Goodrich Copper-Gold Project
Vancouver, BC, Canada — July 28, 2026 — Leads & Copy — Great Plains Metals Corp. announced Tuesday that assay results have confirmed the discovery of a “pencil porphyry” at its Goodrich copper-gold project in New South Wales, Australia. Laboratory assays from drill hole GGDD004 verified a continuous 128-meter intercept of porphyry-style mineralization, validating the company’s exploration thesis that the historical Goodrich mine workings represent the upper portion of an intact porphyry system.
The discovery hole, GGDD004, intersected 128 meters of mineralization with 0.34% copper and 0.17 g/t gold starting at a depth of 81.45 meters. A high-grade zone at the porphyry contact returned 3.55 meters grading 2.80% copper and 0.18 g/t gold from 81.45 meters. Additional sub-intervals within the 128-meter intersection included 26 meters grading 0.52% copper and 0.24 g/t gold from 102 meters, and 5 meters grading 0.66% copper and 0.49 g/t gold from 158 meters.
The Phase One diamond drilling program was designed to test for porphyry-style mineralization beneath the former Goodrich mine. Drill hole GGDD004 intersected significant disseminated copper and gold mineralization hosted within a monzonite porphyry stock. Drill hole GGDD003 intersected altered monzonite porphyry, interpreted as the inner propylitic halo of the Goodrich porphyry.
The mineralized unidirectional solidification textures (USTs) zone intersected at 81.4 meters is considered the cupola contact of the mineralized monzonite porphyry stock. Below this zone, hydrothermal alteration includes pervasive white mica-chlorite and pale albite, potentially overprinting an earlier K-spar-biotite assemblage. The entire 128-meter interval of monzonite porphyry contains disseminated chalcopyrite and pyrite, with traces of molybdenite in rare quartz veins. After 209 meters, the hole transitioned into an inner propylitic zone with increasing epidote, chlorite, and pyrite. Several narrow intercepts of post-mineral trachyte dykes were present throughout the hole.
Drill hole GGDD003 intersected altered chlorite-white mica-epidote monzonite porphyry, considered part of the inner propylitic halo. Two intervals exhibiting UST textures were observed, associated with copper mineralization. A significant fault was intersected at 82 meters, after which mineralization and alteration were weaker.
Two other diamond drill holes, GGDD005 and MRDD001, did not encounter significant mineralization. GGDD005 tested a magnetic high target southeast of the mine but was terminated in unmineralized monzonite/granodiorite. MRDD001, drilled near historical workings at Mt Rose, was terminated in weakly altered monzonite with minor disseminated pyrite.
Additionally, a review of historical core archived at the New South Wales Mines Department facility identified extensive, highly altered intervals in historical drill holes DDHG4 and GRDD01 that were never assayed. A total of 324 samples have been delivered for assay, with results expected within weeks.
Great Plains Metals Corp. previously announced completion of Stage 1 of an Earn-in and Joint Venture Agreement, securing a 51% interest. Stage 2 is expected to result in the company owning a 70% interest. A subsidiary, “GPS Goodrich,” will be formed in New South Wales to hold the project tenements. The Phase Two drill program is anticipated to commence in Q4 2026 following the transfer of land access agreements and approval of work programs.
Peeyush Varshney, CEO, stated, “The results from Drill Hole GGDD004 confirming the discovery of a “pencil porphyry” at Goodrich is a very exciting milestone for GPS. Intersecting 128 meters of copper-gold mineralization starting from just 81 meters from the surface is significant and represents a new exploration opportunity consistent with other porphyry deposits in the Lachlan Fold Belt.”
Great Plains Metals Corp. is an Australia-focused exploration company targeting copper-gold porphyry and critical mineral discoveries. Its flagship Goodrich Project in New South Wales spans 290 km² within the Lachlan Fold Belt. The company also holds a 37.1% equity stake in Eversley Resources, providing exposure to the Eversley North Gawler Craton Project in South Australia.
Source: Great Plains Metals Corp
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