Creedite

Creedite is a hydrated calcium-aluminum sulfate-fluoride mineral that crystallizes as radiating sprays of needle-like crystals. Creedite forms in oxidized zones of fluorite-bearing mineral deposits, where fluorine-rich solutions react with calcium and aluminum minerals. It crystallizes as radiating sprays of acicular (needle-like) crystals that emerge from a central point like a sea urchin or porcupine.

The finest specimens come from Mexico's Navidad Mine in Durango, where vibrant orange creedite clusters grow on beds of dark fluorite. The orange color comes from iron impurities. Chinese specimens tend toward purple or lavender, colored by different trace elements. Colorado material from the type locality near Creede is typically clear to white.

The mineral was first described in 1916 from the Creede mining district in Colorado and named after the town. Despite being known for over a century, creedite remains a relatively obscure mineral appreciated mainly by specimen collectors.

Creedite is identified by its radiating sprays of needle-like crystals growing from a central point. The porcupine-like or hedgehog crystal habit is distinctive. Colors range from clear to orange to purple. Hardness 3.5 and vitreous luster on crystal faces.

Distinguish from aragonite (similar radiating habit but different crystal system and association), scolecite (fibrous but forms in basalt cavities), and natrolite (similar needle habit, different chemistry). The association with fluorite deposits and the characteristic burst-like crystal clusters help identify creedite.