Florencite

Florencite is a rare phosphate mineral with the chemical formula (REE,Ca)Al3(PO4)2(OH)6. It is a member of the florencite group, which are characterized by their layered structure and the presence of rare earth elements. The "REE" in the formula represents a mixture of rare earth elements, with lanthanum and cerium being the most common. Calcium can also substitute for some of the rare earth elements. The other essential components are aluminum and phosphate.

Florencite typically occurs as small, prismatic to tabular crystals, often found in massive or granular aggregates. Its color can vary widely, ranging from colorless and white to shades of yellow, pink, brown, and green. It has a vitreous to dull luster and a hardness of approximately 4.5 on the Mohs scale, making it relatively soft. Florencite is insoluble in common acids.

This mineral is primarily found in pegmatites, granites, and metamorphic rocks. It is also known to occur in hydrothermal veins. Notable occurrences include Brazil, Canada, Norway, and the United States. Florencite is of scientific interest due to its association with rare earth elements, which are vital in many modern technologies, including electronics, magnets, and catalysts. Its rarity and specific geological conditions required for its formation contribute to its status as a mineralogical curiosity.