What is this? Uncle had this since decades and never found out what it this?

Marcasite, with its intriguing cockscomb crystal formations, offers a unique consolation in the realm of minerals. These distinctive crystallizations, resembling the vibrant plume of a rooster’s comb, add a touch of whimsy and beauty to this metallic mineral. While marcasite is valued for its lustrous, pale brass-yellow appearance, it is the cockscomb crystals that capture the imagination. These formations, often delicate and intricate, provide a fascinating contrast to the mineral’s overall composition. For those drawn to the wonders of natural formations, marcasite’s cockscomb crystals offer a captivating reminder of the artistry found within the earth’s depths.