Fluorite

An excellent miniature-sized specimen from Second Chance Mine showcasing beautiful purple fluorite crystals grouped along white planes of quartz that formed as epimorphs after calcite. An attractive testament to the unique mineralogy of Tombstone fluorite!

Tombstone fluorite specimens stand apart from other fluorites for several reasons. Fluorite is a member of the isometric crystal class and occurs in both cubic and octahedral forms, though cubic is far more common. Tombstone crystals, however, range from octahedra to cuboctahedra, with some displaying rounded sides or appearing nearly spherical. While this morphology alone sets them apart, their pairings with quartz and orthoclase add further mineralogical intrigue.

Some specimens, such as this one, feature a type of pseudomorph known as an epimorph, seen here as quartz after calcite. In an epimorph, one mineral forms as a coating along the surfaces of another, and the original mineral later dissolves, leaving a cast of its shape behind. This replacement and dissolution occurred in heavily fractured limestones, where hydrothermal fluids moved through the rock, depositing quartz on calcite while dissolving the calcite itself. The process points to an acidic environment, since quartz forms under the same conditions that dissolve calcite.

Once the quartz pseudomorphs had formed, fluorite filled the voids around them. In some specimens, this appears as glittery white planes extending between groupings of purple fluorite, a pattern collectors often call 'boxwork' or 'boxwork structures.'