Pyrite – Twin, Navajún, Spain (2009)

This Navajún pyrite shows a well-defined twinned cubic growth, with crisp edges and a clear geometric outline. The metallic lustre is consistent across the main faces, while subtle surface textures reflect natural growth features rather than polishing. The specimen is presented on a discreet base that stabilises the piece without obscuring the overall crystal shape.

From the Navajún area in La Rioja (Spain), this pyrite illustrates the locality’s characteristic cube morphology in a compact, well-balanced arrangement. The twinning is easy to read from multiple angles, making the crystal structure immediately understandable even without magnification. With dimensions of 45 × 45 mm, it remains comfortable to observe at arm’s length, while keeping enough volume to appreciate the intergrowth.

🟢 Mineralogical information

- Chemical formula: FeS₂

- Crystal system: Cubic (isometric)

- Hardness: 6 – 6.5 (Mohs)

- Density: About 5.0

- Typical associations: Calcite, quartz, galena

- Specimen shown: Navajún (Spain), 45 × 45 mm, 120 g with base

On this pyrite, the “twin” corresponds to an intergrowth where cubic crystals develop together following a regular geometric relationship. You can see it in the way the volumes interlock and how the edges remain aligned, giving a clear reading of the growth while keeping a stable silhouette for display.