# Tests Confirm Excellent Metallurgy Recovery Canonical Atlas analysis: https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0 Original source: https://www.londonstockexchange.com/news-article/GSCU/tests-confirm-excellent-metallurgy-recovery/17796133 Publisher: lse Original announcement: 2026-09-21T05:24:25.000Z Analysis by Minestarters Atlas Atlas analysis published: 2026-09-21T14:17:55.785Z Atlas analysis updated: 2026-09-21T14:17:55.785Z - Company: Great Southern Copper plc - Ticker: GSCU - Exchange: LSE - Region: Chile - Primary commodity: Copper - Secondary commodities: Silver - Document categories: Drill results, Metallurgy - Extracted: 2026-09-21 14:17:56 UTC Narrative sentiment: 0.80 · Bullish ## Minestarters Atlas summary Great Southern Copper plc announced highly encouraging preliminary metallurgical test results for its high-grade Mostaza Cu-Ag deposit in Chile. Conventional flotation achieved over 90% copper recovery and 87% silver recovery, producing a concentrate grading 27% Cu and 1,414 g/t Ag. The company plans further testwork to optimize grinding conditions and test a broader range of grades, while initial leaching tests showed significantly lower copper recovery. Reasoning: Preliminary metallurgical test results for the Mostaza deposit show excellent copper and silver recoveries and high-grade concentrates using a conventional flotation process, significantly de-risking the project. While the testwork is at a preliminary stage and leaching results were low, the flotation outcomes are highly encouraging. - Positive factor: High copper recovery in flotation - Positive factor: High silver recovery in flotation - Positive factor: High concentrate grades for both copper and silver - Positive factor: Conventional flotation process identified as effective - Positive factor: Potential for further recovery optimization - Positive factor: QP/CP signed off on results - Negative factor: Testwork is preliminary/sighter scale only - Negative factor: Testing limited to high-grade composite samples - Negative factor: Low copper recovery from leaching testwork - Negative factor: Presence of deleterious elements \(arsenic, antimony\) Facts used in scoring: 8 ## Classification and evidence **High Recovery** Polarity: positive Definition: Recovery at or above the exceptional band for the commodity and processing route. Why it applies: Flotation testwork achieved over 90% copper recovery, which is exceptional for the mill route. Evidence · text > Recoveries exceed 90% for copper \(“Cu”\) **High Recovery** Polarity: positive Definition: Recovery at or above the exceptional band for the commodity and processing route. Why it applies: Flotation testwork achieved 87% silver recovery, which is strong for the mill route. Evidence · text > 87% of the silver **Bench Scale Only** Polarity: negative Definition: Only preliminary bench tests completed — no locked-cycle or pilot work. Why it applies: The metallurgical testwork is described as 'preliminary metallurgical test-work' and 'sighter test programme' using 'Batch rougher flotation tests', indicating it is at a bench scale. Evidence · text > preliminary metallurgical test-work on high-grade samples **Deleterious Elements Present** Polarity: negative Story-specific tag Definition: Penalty elements \(arsenic, antimony, etc.\) or refractory concerns noted in the release. Why it applies: Head grade analysis showed 0.27% arsenic, and mineralogy identified tennantite \(arsenic-rich\) and tetrahedrite \(antimony-rich\) as principal copper sulphosalts. Evidence · text > Iron, arsenic and sulphur contents were 0.68%, 0.27% and 1.72%, respectively. **Single Domain Only** Polarity: negative Definition: Testing limited to one composite or domain — representativeness not established. Why it applies: Testwork was conducted on 'two samples of high-grade mineralisation' and a 'high-grade “chalcocite” composite sample', with plans for 'further test-work ... across a broader range of Cu-Ag grades'. Evidence · text > Metallurgical tests on two samples of high-grade mineralisation from the Mostaza deposit **Low Recovery** Polarity: negative Definition: Recovery below the weak band for the commodity and processing route. Why it applies: The ultimate copper recovery to solution from the bottle roll leaching test was just under 50%, which is below the weak band for heap leach copper. Evidence · text > The ultimate copper recovery to solution was just under 50% **Mill Route** Polarity: neutral Definition: Processing via mill or concentrator \(CIL, CIP, tank leach, flotation\). Why it applies: The primary successful processing route identified is a 'conventional flotation recovery process'. Evidence · text > conventional flotation recovery process **Byproduct Commodity** Polarity: neutral Definition: The tested commodity is a byproduct rather than the primary economic driver. Why it applies: Silver is reported alongside copper in the Mostaza deposit and concentrate, indicating it is a byproduct. Evidence · text > Mostaza Cu-Ag deposit **JORC Compliant** Polarity: positive Story-specific tag Definition: Resource estimate prepared in compliance with JORC Code \(Australia\) — high reporting standard. Why it applies: The announcement explicitly states that the information relates to Exploration Results prepared and first disclosed under the JORC Code \(2012\). Evidence · text > JORC Code \(2012\) **QP/CP Signed** Polarity: positive Story-specific tag Definition: Qualified Person \(QP\) or Competent Person \(CP\) named and signed off — a member of a recognized professional association \(e.g., AusIMM, SME, AIG, P.Geo\) with relevant experience. Why it applies: Mr. Jerry Perkins, a qualified metallurgist and FAusIMM\(CPmet\), is named as the consulting metallurgist who conducted the design and supervision of the sighter test programme. Evidence · text > Mr. Jerry Perkins \[FAusIMM\(CPmet\)\] **Heap Leach Route** Polarity: neutral Definition: Processing via heap leach — lower CAPEX and OPEX, lower recovery expected. Why it applies: the document describes a heap\_leach route \("heap leach"\) ## Extracted facts Stored fact records: 8. Some facts used in scoring do not have a stored record. ## Drill Results (6) ### DD005 [Link to this fact](https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0#fact-drill-facts-2) Especularita · copper #### Identity - Hole ID: DD005 - Project: Especularita - Commodity: copper - Region: chile - Reported Region: chile - Ticker: GSCU #### Geometry - Grade: 4.8 - Grade Unit: % - Intercept: 9 m - From: 43 m - To: 52 m - Intercept Depth: 43 m #### Classification - Sample Type: drill - Group ID: DD005:43-52 #### QA/QC - QA/QC Disclosed: Yes - QA/QC Methods: standards, duplicates #### Review - Needs Review: No - Interp. Status: scored - Historical: No #### Dates - Event date: 2026-09-21T00:00:00.000Z Reasoning: Expanded from assay table. 4.8 % copper is exceptional against the default band \[2.5, 1, 0.5, 0.25\] %. Grade×width 43.2 %·m is weak \(grade alone is exceptional; the better of the two is used\). - Positive factor: 4.8 % copper is exceptional on the default band. - Negative factor: Scored from rubric bands during table expansion, not from document context. Evidence · table > 4.8 Context: DD005 #### Tags used in scoring **QA/QC Disclosed** Polarity: positive Definition: Release includes QA/QC disclosure — certified lab, QP sign-off, or stated methods \(blanks, standards, duplicates\). Why it applies: qaqc\_disclosed is true **Cut-off Undisclosed** Polarity: negative Definition: High-grade interval reported without stating the cut-off grade used for compositing. Why it applies: no cutoff\_grade was stated ### DD005 [Link to this fact](https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0#fact-drill-facts-3) Especularita · silver #### Identity - Hole ID: DD005 - Project: Especularita - Commodity: silver - Region: chile - Reported Region: chile - Ticker: GSCU #### Geometry - Grade: 420 - Grade Unit: g/t - Intercept: 9 m - From: 43 m - To: 52 m - Intercept Depth: 43 m #### Classification - Sample Type: drill - Group ID: DD005:43-52 #### QA/QC - QA/QC Disclosed: Yes - QA/QC Methods: standards, duplicates #### Review - Needs Review: No - Interp. Status: scored - Historical: No #### Dates - Event date: 2026-09-21T00:00:00.000Z Reasoning: Expanded from assay table. 420 g/t silver is strong against the default band \[500, 200, 100, 30\] g/t. Grade×width 3780.0 g/t·m is strong. - Positive factor: 420 g/t silver is strong on the default band. - Negative factor: Scored from rubric bands during table expansion, not from document context. Evidence · table > 420 Context: DD005 #### Tags used in scoring **QA/QC Disclosed** Polarity: positive Definition: Release includes QA/QC disclosure — certified lab, QP sign-off, or stated methods \(blanks, standards, duplicates\). Why it applies: qaqc\_disclosed is true **Cut-off Undisclosed** Polarity: negative Definition: High-grade interval reported without stating the cut-off grade used for compositing. Why it applies: no cutoff\_grade was stated ### DD015 [Link to this fact](https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0#fact-drill-facts-4) Especularita · copper #### Identity - Hole ID: DD015 - Project: Especularita - Commodity: copper - Region: chile - Reported Region: chile - Ticker: GSCU #### Geometry - Grade: 5.5 - Grade Unit: % - Intercept: 9.9 m - From: 41.15 m - To: 51.05 m - Intercept Depth: 41.15 m #### Classification - Sample Type: drill - Group ID: DD015:41.15-51.05 #### QA/QC - QA/QC Disclosed: Yes - QA/QC Methods: standards, duplicates #### Review - Needs Review: No - Interp. Status: scored - Historical: No #### Dates - Event date: 2026-09-21T00:00:00.000Z Reasoning: Expanded from assay table. 5.5 % copper is exceptional against the default band \[2.5, 1, 0.5, 0.25\] %. Grade×width 54.5 %·m is weak \(grade alone is exceptional; the better of the two is used\). - Positive factor: 5.5 % copper is exceptional on the default band. - Negative factor: Scored from rubric bands during table expansion, not from document context. Evidence · table > 5.5 Context: DD015 #### Tags used in scoring **QA/QC Disclosed** Polarity: positive Definition: Release includes QA/QC disclosure — certified lab, QP sign-off, or stated methods \(blanks, standards, duplicates\). Why it applies: qaqc\_disclosed is true **Cut-off Undisclosed** Polarity: negative Definition: High-grade interval reported without stating the cut-off grade used for compositing. Why it applies: no cutoff\_grade was stated ### DD015 [Link to this fact](https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0#fact-drill-facts-5) Especularita · silver #### Identity - Hole ID: DD015 - Project: Especularita - Commodity: silver - Region: chile - Reported Region: chile - Ticker: GSCU #### Geometry - Grade: 450 - Grade Unit: g/t - Intercept: 9.9 m - From: 41.15 m - To: 51.05 m - Intercept Depth: 41.15 m #### Classification - Sample Type: drill - Group ID: DD015:41.15-51.05 #### QA/QC - QA/QC Disclosed: Yes - QA/QC Methods: standards, duplicates #### Review - Needs Review: No - Interp. Status: scored - Historical: No #### Dates - Event date: 2026-09-21T00:00:00.000Z Reasoning: Expanded from assay table. 450 g/t silver is strong against the default band \[500, 200, 100, 30\] g/t. Grade×width 4455.0 g/t·m is strong. - Positive factor: 450 g/t silver is strong on the default band. - Negative factor: Scored from rubric bands during table expansion, not from document context. Evidence · table > 450 Context: DD015 #### Tags used in scoring **QA/QC Disclosed** Polarity: positive Definition: Release includes QA/QC disclosure — certified lab, QP sign-off, or stated methods \(blanks, standards, duplicates\). Why it applies: qaqc\_disclosed is true **Cut-off Undisclosed** Polarity: negative Definition: High-grade interval reported without stating the cut-off grade used for compositing. Why it applies: no cutoff\_grade was stated ### DD016 [Link to this fact](https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0#fact-drill-facts-6) Especularita · copper #### Identity - Hole ID: DD016 - Project: Especularita - Commodity: copper - Region: chile - Reported Region: chile - Ticker: GSCU #### Geometry - Grade: 4.7 - Grade Unit: % - Intercept: 7.5 m - From: 89 m - To: 96.5 m - Intercept Depth: 89 m #### Classification - Sample Type: drill - Group ID: DD016:89-96.5 #### QA/QC - QA/QC Disclosed: Yes - QA/QC Methods: standards, duplicates #### Review - Needs Review: No - Interp. Status: scored - Historical: No #### Dates - Event date: 2026-09-21T00:00:00.000Z Reasoning: Expanded from assay table. 4.7 % copper is exceptional against the default band \[2.5, 1, 0.5, 0.25\] %. Grade×width 35.3 %·m is weak \(grade alone is exceptional; the better of the two is used\). - Positive factor: 4.7 % copper is exceptional on the default band. - Negative factor: Scored from rubric bands during table expansion, not from document context. Evidence · table > 4.7 Context: DD016 #### Tags used in scoring **QA/QC Disclosed** Polarity: positive Definition: Release includes QA/QC disclosure — certified lab, QP sign-off, or stated methods \(blanks, standards, duplicates\). Why it applies: qaqc\_disclosed is true **Cut-off Undisclosed** Polarity: negative Definition: High-grade interval reported without stating the cut-off grade used for compositing. Why it applies: no cutoff\_grade was stated ### DD016 [Link to this fact](https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0#fact-drill-facts-7) Especularita · silver #### Identity - Hole ID: DD016 - Project: Especularita - Commodity: silver - Region: chile - Reported Region: chile - Ticker: GSCU #### Geometry - Grade: 340 - Grade Unit: g/t - Intercept: 7.5 m - From: 89 m - To: 96.5 m - Intercept Depth: 89 m #### Classification - Sample Type: drill - Group ID: DD016:89-96.5 #### QA/QC - QA/QC Disclosed: Yes - QA/QC Methods: standards, duplicates #### Review - Needs Review: No - Interp. Status: scored - Historical: No #### Dates - Event date: 2026-09-21T00:00:00.000Z Reasoning: Expanded from assay table. 340 g/t silver is strong against the default band \[500, 200, 100, 30\] g/t. Grade×width 2550.0 g/t·m is moderate \(grade alone is strong; the better of the two is used\). - Positive factor: 340 g/t silver is strong on the default band. - Negative factor: Scored from rubric bands during table expansion, not from document context. Evidence · table > 340 Context: DD016 #### Tags used in scoring **QA/QC Disclosed** Polarity: positive Definition: Release includes QA/QC disclosure — certified lab, QP sign-off, or stated methods \(blanks, standards, duplicates\). Why it applies: qaqc\_disclosed is true **Cut-off Undisclosed** Polarity: negative Definition: High-grade interval reported without stating the cut-off grade used for compositing. Why it applies: no cutoff\_grade was stated ## Metallurgical Results (2) ### bottle roll [Link to this fact](https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0#fact-metallurgical-facts-0) Especularita · copper #### Identity - Project: Especularita - Commodity: copper - Region: chile - Reported Region: Chile - Ticker: GSCU #### Test Work - Program Status: scoping - Test Type: bottle roll - Processing Route: sulphuric acid and salt leaching - Sample: high-grade composite, crushed to minus 2mm - Leach Time: 168 hours #### Recovery - Recovery: 50 % - Recovery Basis: actual\_test - Head Grade: 5.09 - Head Grade Unit: % #### Reagents - Reagent Notes: The pH was adjusted to 1.5 with sulphuric acid, and approximately 450kg/t of salt \(sodium chloride\) were added and ferrous sulphate to 5g/litre. #### Lab - Laboratory: Aminpro - Consultant: Mr. Jerry Perkins #### Review - Needs Review: No - Historical: No #### Dates - Event date: 2026-09-21T00:00:00.000Z Reasoning: The copper recovery from the bottle roll leaching test was significantly lower than flotation, indicating this may not be the optimal processing route for the material tested. - Negative factor: Low copper recovery from leaching testwork - Negative factor: Testwork is preliminary/scoping scale - Negative factor: Testing limited to high-grade samples - Negative factor: Presence of deleterious elements Evidence · text > The ultimate copper recovery to solution was just under 50% #### Tags used in scoring **Low Recovery** Polarity: negative Definition: Recovery below the weak band for the commodity and processing route. Why it applies: 50% is below the weak band \(80%\) ### flotation [Link to this fact](https://atlas-staging.minestarters.com/news/tests-confirm-excellent-metallurgy-recovery--f549856a-6c0e-4cd1-a226-f7373a840cf0#fact-metallurgical-facts-1) Especularita · silver #### Identity - Project: Especularita - Commodity: silver - Region: chile - Reported Region: Chile - Ticker: GSCU #### Test Work - Program Status: preliminary - Test Type: flotation - Processing Route: conventional flotation - Sample: high-grade chalcocite composite sample - Grind P80: 180 µm #### Recovery - Recovery: 87 % - Recovery Basis: actual\_test - Head Grade: 279 - Head Grade Unit: g/t - Conc. Grade: 1414 - Conc. Grade Unit: g/t #### Reagents - Reagent Notes: AP3894 \(Thiocarbamate – 10g/t\) added during grinding, followed by PAX/SIPX \(20 g/t\) and MIBC \(15 g/t\) added during conditioning. #### Lab - Laboratory: Aminpro - Consultant: Mr. Jerry Perkins #### Review - Needs Review: No - Historical: No #### Dates - Event date: 2026-09-21T00:00:00.000Z Reasoning: The flotation test achieved excellent silver recovery and a high-grade concentrate, indicating a viable processing route for the deposit. - Positive factor: High recovery for silver - Positive factor: High concentrate grade for silver - Positive factor: Conventional process identified - Positive factor: Potential for further optimization - Negative factor: Testwork is preliminary/sighter scale - Negative factor: Testing limited to high-grade samples - Negative factor: Presence of deleterious elements Evidence · text > Recoveries ... 85% for silver \(“Ag”\) resulting in a final concentrate with grades averaging ... 1,414 g/t Ag #### Tags used in scoring **Mill Route** Polarity: neutral Definition: Processing via mill or concentrator \(CIL, CIP, tank leach, flotation\). Why it applies: processing\_route matches the flotation signal ## How Atlas produces this analysis Minestarters Atlas uses automated extraction to summarize mining announcements, identify reported measurements, and classify supporting evidence. Sentiment reflects the extracted narrative and classification rules; it is an interpretation, not a reported measurement. Evidence quotes and context are provided where available. Missing data, low-confidence results, and review flags indicate limitations. Check the original publisher announcement before relying on an interpretation.