Koodeksite

Koodeksite is a rare mineral belonging to the phosphate group. Its chemical formula is NaCaMgFe³⁺(PO₄)₂. Koodeksite is known for its striking azure blue color, which is attributed to the presence of iron in its trivalent state. The mineral typically crystallizes in the triclinic system, forming small, prismatic crystals. It is often found as an accessory mineral in metamorphic rocks, particularly in crystalline limestones and marbles. It can also occur in some pegmatites.

The type locality for koodeksite is the Kōdō mine in the Fukui Prefecture of Japan, from which it derives its name. It was first described in 1982. While not a commercially important mineral, koodeksite is of interest to mineralogists due to its unique chemical composition and occurrence. It is relatively soft, with a Mohs hardness of around 4.5, and has a vitreous luster. It is insoluble in common acids. Other localities where koodeksite has been reported include parts of Norway, the United States, and Greenland. Its presence often indicates specific geological conditions involving the interaction of phosphate-rich fluids with carbonate rocks.