Ferrowodginite

Chemical formula: Fe₂+Sn₄+Ta₅+₂O₈

Ferrowodginite is a rare, black oxide mineral from the wodginite group, containing iron, tin, and tantalum.

## Characteristics Ferrowodginite is a very rare mineral from the wodginite group, belonging to the oxide class. It usually forms small, poorly developed crystals up to 1 mm in size, often occurring in intergrowths with other tantalum minerals. It is opaque and black in color. ## Physical Properties This mineral is characterized by a hardness of 5.5 on the Mohs scale. It has a luster described as metallic to submetallic. Its density is high, which is typical for tantalum-bearing minerals. ## Colors and Varieties Ferrowodginite occurs in a uniform, black color. No colored varieties are known. ## History and Name The name "ferrowodginite" refers to its chemical composition - the dominance of iron (Latin: *ferrum*) and its relation to the structurally similar mineral, wodginite. It was first described in 1984 based on material from the Tanco pegmatite, Bernic Lake area, Manitoba (Canada). ## Uses Due to its extreme rarity, ferrowodginite has no industrial application. It is solely an object of scientific interest and a collector's item for specialized collectors of rare minerals.

Properties

Mohs hardness: 5.5
Luster: Sub-Metallic
Streak: Brown
Density: 7.16
Cleavage: None
Fracture: Sub-Conchoidal
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of ferrowodginite is extremely difficult without advanced analytical methods. It can be preliminarily recognized by its black color, metallic luster, and co-occurrence with other tantalum minerals in granitic pegmatites. Final confirmation requires chemical analysis (e.g., EDS) and X-ray diffraction (XRD). ## Distinguishing from Similar Minerals It can be confused with other black, heavy oxide minerals such as wodginite, ferrotapiolite, tantalite-(Fe), or ilmenite. Visual differentiation is practically impossible and requires specialized laboratory tests to determine the exact chemical composition and crystal structure. ## Crystal Forms Most often, it forms granular, anhedral (undeveloped) aggregates or poorly developed, tabular crystals, usually small in size, not exceeding 1 mm.

Geological environment

## Genesis Ferrowodginite is a mineral of magmatic origin, crystallizing in the late stages of evolution of highly differentiated granitic pegmatites, especially those rich in lithium, cesium, and tantalum (LCT-type pegmatites). ## Mineral Associations It usually co-occurs with other tantalum and tin-bearing minerals, such as wodginite, tantalite-(Mn), tapiolite-(Fe), cassiterite, as well as with albite, microcline, and quartz. ## Localities The most important and best-documented locality, which is also the type locality, is the Tanco mine in the Bernic Lake area, Manitoba, Canada. This mineral has also been identified in pegmatites in Sukula, Finland, and in Russia.

Rarity

Very rare

For collectors

## Quality Criteria The collector's appeal of ferrowodginite is not based on aesthetics, but on its extreme rarity. The most desirable specimens are those where the mineral is clearly visible, even as a small grain, and unambiguously identified analytically. The presence of well-formed, even microscopic, crystals and rich associations with other rare minerals increases its value. ## Popular Localities The only source of specimens available on the collector's market is the Tanco mine in Manitoba, Canada. Specimens from other localities are practically unavailable and are of scientific interest only.

Care and storage

## Cleaning Specimens should only be cleaned mechanically, using a soft brush to remove dust. The use of water or any chemical agents is not recommended to avoid potential reactions, especially with associated minerals. ## What to Avoid Avoid contact with chemicals, acids, and bases. The mineral is brittle, so it must be protected from impacts and falls. It should not be subjected to ultrasonic cleaning. ## Storage It is recommended to store specimens under stable conditions, in closed display boxes that protect against dust and mechanical damage. It is advisable to isolate it from other minerals to prevent abrasion.

Sources

IMA Mineral List (CNMNC)