Pyrochloremineralen

Pyrochlore is a mineral group with the general formula A2B2O7. The 'A' site is typically occupied by cations such as rare earth elements, sodium, calcium, or uranium, while the 'B' site is usually occupied by niobium, tantalum, or titanium. This mineral group is a significant source of niobium and tantalum, which are used in various industries including steel production, electronics, and aerospace.

Pyrochlore minerals crystallize in the cubic crystal system and often form as small, euhedral crystals or massive aggregates. They are typically found in alkalic igneous rocks, particularly in carbonatites and syenites. The color of pyrochlore can vary widely, ranging from yellow and brown to black, depending on the specific chemical composition and the presence of impurities.

The pyrochlore structure is characterized by a framework of corner-sharing BO6 octahedra, with the A cations occupying interstitial sites within this framework. Due to the variability of the A and B site cations, there is a broad compositional range within the pyrochlore supergroup, leading to numerous named species such as microlite, koppite, and betafite. These variations in composition can influence the physical properties of the minerals, including their hardness and specific gravity. Pyrochlore minerals are generally considered to be relatively hard, with Mohs hardness values typically between 5 and 5.5.