Millerite, Calcite

This specimen is a striking example that displays long, hair-like needles of millerite, delicately perched atop and surrounding a calcite crystal within a quartz-lined geode. The spectacular piece comes with a label marked simply “Harrodsburg, Indiana,” and is most likely from the well-known geode-producing roadcut along State Route 37—long popular among collectors.

The brassy millerite crystals exhibit a fine, filamentous structure, forming shimmering, golden nests of needles across the chalcedony-lined cavity. These intricate fibres crisscross the calcite, typical of the locality, though rarely seen at this impressive scale.

The mineralization occurs within the Harrodsburg Limestone, part of the Middle Mississippian strata, where geodes were once found on both sides of the roadcut. Millerite specimens of this calibre were collected primarily in the 1970s and 1980s, though the site is now closed to collectors if I'm not mistaken. Specimens from this locality are increasingly rare, and this unusually large and well-preserved example represents a museum-worthy piece and an outstanding addition to any cabinet collection.