Ixiolite

Sitting on a bit of quartz matrix is a black Ixiolite crystal. Many of the crystal faces can be seen with some bruising around the edges. Ixiolite is a rare, complex rare-earth element (REE) oxide typically found in tantalum-bearing granitic pegmatites. The mineral often forms lustrous, metallic crystals that can display a striking appearance. Ixiolite is an accessory oxide mineral and is closely associated with other tantalum-rich minerals such as microlite, tantalite, tapiolite, and wodginite, all of which are significant sources of tantalum—a critical element in various high-tech industries.

Notably, ixiolite contains about 69% tantalum oxide (Ta₂O₅), making it a key mineral in tantalum extraction. Its occurrence is limited to specialized environments like granitic pegmatites, where the conditions are suitable for the formation of these rare minerals.