• Four options, A and B on top, and C and D on the bottom. Option A has large silver-gold squares of pyrite across the surface, the iridescence around them pink and purple and the rest more blue and green. Option B is blocky and electric blue-green with blue patches. Option C is long and thin, with one large pyrite cube, the rest a muddled mix of yellow-green and aqua blue. Option D is blocky and triangular, the luster duller than the others, but with deep green-blue and pink-purple color.
  • Close view of a pile of rough chunks of chalcopyrite with different iridescent colors. The one in the focus at center is pink-purple with orange and blue flashes. The pieces around it have a mix of yellow-green, blue-green, blue, violet, and purple iridescence.
  • Example piece, corresponding with option A. This piece has a full rainbow, a small amount of yellow on the end then green, aqua, blue, violet, purple, and pink. Silver-gold cubes of pyrite run through the piece.
  • Options E through H. Option E is blocky with a patchy mix of yellow-green and aqua-blue, and spotted with pyrite cubes in areas. Option F is long and narrow and curved, with a gradient from yellow-green to violet-blue and a few purple spots. Option G is a blocky wedge, luster duller than the others, a deep blue with violet and purple patches and spotted with small pyrites like a night sky. Option H is long and teardrop-shaped, vivid yellow green and aqua with several large pyrites.
  • Options I through L. Option I is long, narrow, and angled, patchy aqua blue and violet-purple, with triangular pyrite corners across the surface. Option J is blocky and triangular, a patchy mix of vivid blue and pink-purple. Option K a blocky and compact, with electric blue-green iridescence. Option L is rectangular with pyrite cubes scattered across one end, the iridescence behind them golden-orange with a gradient spreading out to purple, then blue and green-blue.
  • Options M through P. Option M is blocky and wedge-shaped, with thin white quartz veins crossing it and white patches, and vivid aqua blue, blue, and pink-purple iridescence. Option N is long and wedge-shaped, with electric aqua blue-green iridescence. Option O is blocky with large patches of pink-purple and aqua blue iridescence, with some orange. Option P is long and angled, bright aqua blue with a bit of violet and purple pattern.
  • Diagram showing that the chalcopyrite can contain additional minerals, identify quartz on the left which can appear as white patches or thin veins through the rock. On the right is an example of pyrite, a gold square in the surface of the chalcopyrite, which can appear as gold patches or cubes.
  • Scale image of options A through P on a measuring mat. They are all roughly the same size with options N, H, B, and C on the smaller side, and options A, D, E, J, K, and P on the larger side.
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Iridescent chalcopyrite, 2.5–3" piece

Iridescent chalcopyrite, 2.5–3" piece

$10.00 USD
$10.00 USD
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Locality: Mexico

Approx size: 2.5–3"

Approx weight: 75–275g, avg 200g

**Altered material

 

Iridescent chalcopyrite is frequently sold as "peacock ore" due to its jewel-tone mix of blue, green, purple, and gold. If pyrite is fool's gold, then this variety of chalcopyrite is fool's bornite: it borrows its trade name from the closely related mineral bornite, the original peacock ore. The same process causes vibrant iridescence in both minerals by tarnishing the metallic surface into iridescent color: bornite naturally oxidizes on exposure to air, and exposure to acid chemically induces a similar tarnish in chalcopyrite.

Chalcopyrite's tarnishing process can occur naturally, but the brightly-colored chunks of material most commonly found on the market have been treated: they have undergone an acid bath to rapidly achieve a strong tarnish. Essentially people have taken advantage of the material's natural properties to bring out the rainbow iridescence. Since chalcopyrite is a much more abundant mineral compared to bornite, this treated material is the inexpensive stuff you typically see for sale as "peacock ore" at souvenir and rock shops across the southwestern US. Unfortunately it is often sold as bornite, lending to chalcopyrite's reputation as the "faux peacock ore."

The brilliant colors form an extremely thin layer on the surface, but the chalcopyrite beneath is a gold-colored mineral that is often mistaken for pyrite. It is a copper-based metallic mineral with a similar weighty heft to pyrite, but is softer and more prone to scratches, flaking, and crumbling compared to pyrite. Pyrite often grows along with chalcopyrite, and is included in many of the vials; it does not respond to the acid bath and remains a metallic gold tone. Chalcopyrite is also often accompanied by minerals like quartz (forming white veins and patches), calcite, bornite, and galena.

⚠️ BRITTLE WARNING chalcopyrite is relatively soft (3.5–4 on the Mohs scale), and can be scratched or broken. It is common for small pieces to crumble off the surface during handling, and is brittle enough that thinner pieces can be snapped in half by hand.

❗ STAINING WARNING chalcopyrite can leave black spots or streaks on skin, clothing, and surfaces; be prepared for black fingers after handling. I recommend cork coasters under messy minerals as an inexpensive way to protect surfaces.

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