Ferrotitanowodginite

Chemical formula: Fe₂+Ti₄+Ta₅+₂O₈

Ferrotitanowodginite is a rare, black oxide mineral of the wodginite group, found in granitic pegmatites.

## Characteristics Ferrotitanowodginite is a very rare mineral of the wodginite group, belonging to the oxide class. It forms small, tabular or prismatic crystals, usually not exceeding a few millimeters in size. It most often occurs as inclusions in other minerals, mainly in quartz or albite. It is opaque and has a black color. ## Physical Properties This mineral is characterized by a hardness of 6-6.5 on the Mohs scale. It has a metallic to submetallic luster. Its density is high, approximately 7.2 g/cm³, which is typical for tantalum-bearing minerals. ## Colors and Varieties Ferrotitanowodginite is a mineral with a consistent, black color. No color varieties or commercial varieties are distinguished. ## History and Name The name "ferrotitanowodginite" refers to its chemical composition – the dominance of iron (ferro) and titanium (titano) – and its structural relationship with wodginite, another mineral from the same group. It was first described by T. S. Ercit and colleagues in 1992 based on material from the Tanco Mine in Bernic Lake, Manitoba, Canada. ## Applications Due to its extreme rarity, ferrotitanowodginite has no industrial applications. It is solely an object of scientific interest and a collector's item for specialized collectors (so-called micromounters).

Properties

Mohs hardness: 6-6.5
Luster: Metallic to submetallic
Streak: Black
Density: 7.2
Cleavage: Imperfect on {010}
Fracture: Uneven to conchoidal
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of ferrotitanowodginite is extremely difficult and impossible without advanced analytical methods. Preliminary identification is based on its black color, metallic luster, high density, and occurrence in a specific geological environment (lithium pegmatites). Final confirmation requires chemical analysis (EDS/WDS) to confirm the presence of iron, titanium, and tantalum as dominant elements. ## Distinguishing from Similar Minerals It can be confused with other black, heavy pegmatite minerals, such as columbite, tantalite, wodginite, ferrowodginite, or ilmenite. Visual differentiation is practically impossible. Wodginite and ferrowodginite have a similar structure but different chemical compositions (dominance of manganese and tin, or iron alone without titanium, respectively). Columbite-tantalite has a different crystal habit and usually forms larger aggregates. ## Crystal Forms Crystals are usually very small, with a tabular or short-prismatic habit. They often occur as irregular grains or inclusions in other pegmatite minerals.

Geological environment

## Genesis Ferrotitanowodginite is a mineral of magmatic origin, crystallizing in the late stages of the evolution of highly differentiated granitic pegmatites, especially those rich in lithium, cesium, and tantalum (LCT-type pegmatites). ## Mineral Associations It most commonly co-occurs with quartz, albite (especially its cleavelandite variety), microcline, wodginite, tantalite-(Mn), tapiolite-(Fe), and pollucite. ## Localities The most important and well-documented occurrences of this mineral worldwide include: - Tanco Mine, Bernic Lake, Manitoba, Canada (type locality). - Red Cross Lake Pegmatite, Manitoba, Canada. - Alto Ligonha area in Mozambique.

Rarity

Very rare

For collectors

## Quality Criteria The collector's appeal of ferrotitanowodginite is primarily determined by the quality and development of the crystals, despite their microscopic size. Specimens with sharp, well-defined crystals, set against a contrasting background (e.g., on white albite), are most valued. The certainty of identification, confirmed by chemical analysis, is also important. ## Popular Localities The most known and valued specimens, although still microscopic, come from the type locality – the Tanco Mine in Canada.

Care and storage

## Cleaning Specimens should only be cleaned with compressed air to remove dust. Due to the small size of the crystals and their occurrence as inclusions, mechanical or chemical cleaning is inadvisable and risky. ## What to Avoid Avoid contact with acids and other chemicals. Do not subject specimens to ultrasonic cleaners, as this may damage delicate crystals or the host rock. ## Storage Ferrotitanowodginite specimens, typically as micromounts, should be stored in stable conditions, in specialized boxes protecting against dust and mechanical damage. It is not sensitive to light.

Sources

IMA Mineral List (CNMNC)