Category:
Mineral
Material Type:
non-metal
Alternative Names:
Tags:
Chalcopyrite (CuFeS₂) Mineral
Mineral
Basic Information
Composition & Structure
Composition:
CuFeS₂, often with MoS₂, pyrite, and gangue minerals
Microstructure:
Crystalline sulfide mineral grains, often interlocked with other mineral phases
Description
Chalcopyrite is the most important copper ore mineral. Metallographic examination is essential for mineral liberation analysis — determining whether valuable minerals have been adequately freed from gangue material during grinding. Preparation must maintain the ore concentrate structure without liberating locked minerals, which would produce misleading analysis results.
Mechanical Properties
Hardness:
3.5-4 Mohs, ~200 HV
Hardness Category:
medium hard
Physical Properties
Density:
4.1-4.3 g/cm³
Melting Point:
~950 °C (decomposes)
Material Characteristics
Work Hardening:
No
Magnetic:
No
Corrosion Resistance:
low
Sectioning
Not required for mineral concentrates. Samples are loose particles embedded in mounting resin.
Mounting
Castable with epoxy or acrylic. Mix mineral powder with epoxy. Vacuum impregnation ensures filling between particles. Proper particle distribution is critical.
Grinding
Start at 240 grit SiC. Very light pressure (5 lbs / ~22 N) and slow speed (100/100 rpm) to prevent particle dislodgement.
Grinding sequence:
Grinding sequence:
- 240 SiC: Planar grinding to establish flat surface.
- 360 SiC: Remove previous scratches (1 min).
- 600 SiC: Remove previous scratches (1 min).
Recommended Sequence:
Polishing
Very light pressure throughout to prevent particle dislodgement.
Polishing sequence:
Polishing sequence:
- 6μm diamond: 5 minutes on TEXPAN with DIALUBE Purple (100/100 rpm).
- 1μm diamond: 5 minutes on GOLDPAD/ATLANTIS with DIALUBE Purple (100/100 rpm).
- SIAMAT colloidal silica: 5 minutes on TEXPAN (100/100 rpm).
Recommended Sequence:
Etching
Examined as-polished in reflected light. Chalcopyrite has distinctive brass-yellow color. HNO₃ tarnish test for identification (drop of conc. HNO₃ produces iridescent tarnish on chalcopyrite, not pyrite). KMnO₄ stains chalcopyrite brown. Polarized light reveals bireflectance.
Common Etchants:
Heat Treatment
Not applicable — natural mineral.
Relevant Standards
- ASTM E1382
- ISO 13322
Applications
- Mineral liberation analysis
- Flotation process optimization
- Ore grade assessment
- Mine geology characterization
Typical Uses
- Copper concentrator QC
- Molybdenum recovery optimization
- Tailings analysis
- Geometallurgical mapping