Spanish Pyrite Cubes

Spanish pyrite, also known as “pyrite cubes,” is a distinctive variety of pyrite found primarily in the coal mines of northern Spain, particularly in the Asturias region. These remarkable specimens consist of perfect to near-perfect cubic crystals embedded within limestone matrix.

The pyrite cubes are renowned for their exceptional clarity, geometric perfection, and vibrant brassy-yellow coloration. They often form intricate geometric patterns within the surrounding rock, creating visually striking displays highly prized by mineral collectors worldwide.

The formation of Spanish pyrite cubes is attributed to geological processes that occurred millions of years ago. During the Carboniferous period, the region that is now northern Spain was covered by shallow seas. Over time, organic matter accumulated on the seafloor, forming limestone deposits. As sedimentation continued, the organic matter decayed, releasing sulfur compounds that reacted with iron minerals in the surrounding rock, ultimately leading to the formation of pyrite crystals.

The unique geological conditions in northern Spain, including the presence of coal seams and sulfur-rich limestone, contributed to the formation of these exquisite pyrite specimens. Today, Spanish pyrite cubes are highly sought after by collectors for their rarity, beauty, and geological significance, representing a fascinating chapter in the Earth’s history and the wonders of natural mineral formation.