Tests Confirm Excellent Metallurgy Recovery
Original announcement by lse on
- 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
Analysis by Minestarters Atlas
Atlas analysis published:
Minestarters Atlas analysis
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 factors
- High copper recovery in flotation
- High silver recovery in flotation
- High concentrate grades for both copper and silver
- Conventional flotation process identified as effective
- Potential for further recovery optimization
- QP/CP signed off on results
Negative factors
- Testwork is preliminary/sighter scale only
- Testing limited to high-grade composite samples
- Low copper recovery from leaching testwork
- Presence of deleterious elements (arsenic, antimony)
Facts used in scoring: 8
Classification and evidence
High Recoverypositive
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 Recoverypositive
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 Onlynegative
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 Presentnegative · Story-specific tag
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 Onlynegative
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 Recoverynegative
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 Routeneutral
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 Commodityneutral
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 Compliantpositive · Story-specific tag
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 Signedpositive · Story-specific tag
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 Routeneutral
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)
DD005Especularita · copperGrade: 4.8Grade Unit: %Intercept: 9 mView all detailsHide details
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 factors
- 4.8 % copper is exceptional on the default band.
Negative factors
- Scored from rubric bands during table expansion, not from document context.
Evidence · table
“4.8”
Context: DD005
Tags used in scoring
QA/QC Disclosedpositive
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 Undisclosednegative
High-grade interval reported without stating the cut-off grade used for compositing.
Why it applies: no cutoff_grade was stated
DD005Especularita · silverGrade: 420Grade Unit: g/tIntercept: 9 mView all detailsHide details
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 factors
- 420 g/t silver is strong on the default band.
Negative factors
- Scored from rubric bands during table expansion, not from document context.
Evidence · table
“420”
Context: DD005
Tags used in scoring
QA/QC Disclosedpositive
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 Undisclosednegative
High-grade interval reported without stating the cut-off grade used for compositing.
Why it applies: no cutoff_grade was stated
DD015Especularita · copperGrade: 5.5Grade Unit: %Intercept: 9.9 mView all detailsHide details
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 factors
- 5.5 % copper is exceptional on the default band.
Negative factors
- Scored from rubric bands during table expansion, not from document context.
Evidence · table
“5.5”
Context: DD015
Tags used in scoring
QA/QC Disclosedpositive
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 Undisclosednegative
High-grade interval reported without stating the cut-off grade used for compositing.
Why it applies: no cutoff_grade was stated
DD015Especularita · silverGrade: 450Grade Unit: g/tIntercept: 9.9 mView all detailsHide details
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 factors
- 450 g/t silver is strong on the default band.
Negative factors
- Scored from rubric bands during table expansion, not from document context.
Evidence · table
“450”
Context: DD015
Tags used in scoring
QA/QC Disclosedpositive
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 Undisclosednegative
High-grade interval reported without stating the cut-off grade used for compositing.
Why it applies: no cutoff_grade was stated
DD016Especularita · copperGrade: 4.7Grade Unit: %Intercept: 7.5 mView all detailsHide details
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 factors
- 4.7 % copper is exceptional on the default band.
Negative factors
- Scored from rubric bands during table expansion, not from document context.
Evidence · table
“4.7”
Context: DD016
Tags used in scoring
QA/QC Disclosedpositive
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 Undisclosednegative
High-grade interval reported without stating the cut-off grade used for compositing.
Why it applies: no cutoff_grade was stated
DD016Especularita · silverGrade: 340Grade Unit: g/tIntercept: 7.5 mView all detailsHide details
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 factors
- 340 g/t silver is strong on the default band.
Negative factors
- Scored from rubric bands during table expansion, not from document context.
Evidence · table
“340”
Context: DD016
Tags used in scoring
QA/QC Disclosedpositive
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 Undisclosednegative
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 rollEspecularita · copperRecovery: 50 %Head Grade: 5.09Head Grade Unit: %View all detailsHide details
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 factors
- Low copper recovery from leaching testwork
- Testwork is preliminary/scoping scale
- Testing limited to high-grade samples
- Presence of deleterious elements
Evidence · text
“The ultimate copper recovery to solution was just under 50%”
Tags used in scoring
Low Recoverynegative
Recovery below the weak band for the commodity and processing route.
Why it applies: 50% is below the weak band (80%)
flotationEspecularita · silverRecovery: 87 %Head Grade: 279Head Grade Unit: g/tView all detailsHide details
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 factors
- High recovery for silver
- High concentrate grade for silver
- Conventional process identified
- Potential for further optimization
Negative factors
- Testwork is preliminary/sighter scale
- Testing limited to high-grade samples
- 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 Routeneutral
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.