Ferrotantalite

Ferrotantalite is an iron-rich member of the tantalite group within the columbite-tantalite series. It is typically described by the solid-solution formula (Fe2+, Mn2+)Ta2O6, with iron predominating in many samples. End-members include ferrotantalite (Fe-rich) and manganotantalite (Mn-rich), and intermediate compositions are common due to Fe–Mn substitution.

Ferrotantalite forms in granitic pegmatites and hydrothermal environments, often crystallizing as coarse-grained prisms or masses. It commonly occurs together with other tantalum- and niobium-bearing minerals, such as tantalite and columbite, and with quartz, spodumene, lepidolite, and other rare-element minerals.

In hand specimen, ferrotantalite appears black to brownish-black with a metallic to submetallic luster and is opaque. It is a very dense mineral, reflecting the presence of tantalum, and can be relatively hard compared with many other accessory minerals. The mineral is typically identified by its chemical composition and associations, as distinguishing ferrotantalite from related tantalum niobate minerals often requires analytic techniques.

Economic and practical significance lies in its relationship to tantalum production. Ferrotantalite is part of the same mineral group that yields tantalum, which is refined from tantalite-tantalite-oxide concentrates into Ta2O5 for use in electronics, capacitors, and specialty alloys. The exact determination of end-member composition is of interest to ore evaluators and mineralogists for understanding the tantalum resource.