What is the Difference Between Pyrite and Chalcopyrite?

Pyrite and chalcopyrite are both sulfide minerals, but they have different chemical compositions, appearances, and physical properties. Here are the main differences between the two:

1. Chemical Composition: Pyrite is an iron sulfide mineral with the chemical formula FeS2, while chalcopyrite is a copper iron sulfide mineral with the chemical formula CuFeS2.
2. Appearance: Pyrite has a pale brass yellowish color with a metallic luster, while chalcopyrite is brassy to golden yellowish in color. Chalcopyrite often displays an iridescent tarnish, which pyrite does not.
3. Hardness: Pyrite is a harder mineral than chalcopyrite. It has a Mohs hardness of 6 to 6.5, while chalcopyrite has a hardness of 3.5 to 4.
4. Crystal Habits: Pyrite typically occurs in well-crystallized shapes of octahedrons and pyritohedrons (dodecahedral), while chalcopyrite is more commonly found as groups of small, distorted crystals in globular or botryoidal shapes.
5. Oxidization: Pyrite oxidizes slowly in a moist environment, discharging sulfuric acid, while chalcopyrite oxidizes more rapidly, producing bright colors.

To summarize, pyrite is a harder mineral with a pale brass yellow color, while chalcopyrite is softer, with a brassy to golden yellow color and an iridescent tarnish. Pyrite has octahedral or pyritohedral crystal shapes, whereas chalcopyrite has distorted crystals in globular or botryoidal shapes.

Comparative Table: Pyrite vs Chalcopyrite

Here is a table comparing the differences between pyrite and chalcopyrite:

Pyrite and chalcopyrite are both sulfide minerals, but they have different chemical compositions and physical properties. While pyrite contains iron sulfide (FeS2), chalcopyrite is a copper iron sulfide mineral with the chemical formula CuFeS2. Pyrite has a pale brass yellowish color with a metallic luster, while chalcopyrite is brassy to golden yellowish in color. Pyrite has a cubic crystal system and is relatively harder compared to chalcopyrite, which has a hardness of 3.5-4.