Lithiowodginite

Chemical formula: LiTa₅+₃O₈

Lithiotapiolite is a very rare oxide mineral, a lithium and tantalum compound, found almost exclusively in one location worldwide.

## Characteristics Lithiotapiolite is a mineral belonging to the wodginite group, distinguished by the presence of lithium in its chemical composition. It typically forms small, anhedral (irregular) grains or subhedral (partially formed) crystals, rarely exceeding a few millimeters. Its color is dark, ranging from reddish-brown to almost black, and its luster is described as submetallic. Due to its rarity and inconspicuous appearance, it is a mineral primarily of interest to specialized collectors and scientists. ## Physical Properties This mineral is characterized by a hardness of 5.5 on the Mohs scale and a significant density, reaching 7.98 g/cm³, which is typical for tantalum minerals. It is opaque; only very thin fragments may be translucent. It exhibits no cleavage, and its fracture is subconchoidal to uneven. ## Colors and Varieties Lithiotapiolite occurs in a limited color range, from dark reddish-brown to black. No color varieties or commercial varieties are distinguished for it. ## History and Name The mineral's name refers to its chemical composition – the presence of lithium (Latin: *lithium*) – and its structural similarity to wodginite. It was officially described as a new mineral species in 1992 by T. Scott Ercit, Petr Černý, and Frank C. Hawthorne based on material from the type locality in Canada. ## Applications Due to its extreme rarity, lithiotapiolite has no industrial applications. It serves solely as an object of scientific research and a valuable specimen in advanced systematic collections.

Properties

Mohs hardness: 5.5
Luster: Submetallic
Streak: Red-brown
Density: 7.98
Cleavage: None
Fracture: Subconchoidal to uneven
Transparency: Opaque, translucent in thin fragments
Crystal system: Monoclinic

Diagnostic features

## Identification Helpful features for identifying lithiotapiolite include its high density (the specimen feels heavy for its size), dark color, submetallic luster, and hardness. However, the key is its occurrence – almost always in LCT-type (lithium-cesium-tantalum) pegmatites – and its association with other rare tantalum minerals. ## Distinguishing from Similar Minerals Lithiotapiolite is visually almost impossible to distinguish from wodginite, tantalite, or columbite. Wodginite does not contain lithium, and its composition is dominated by manganese, tin, and tantalum. Tantalite and columbite have different crystal structures. Reliable differentiation of these minerals requires advanced analytical methods, such as X-ray microanalysis (EDS/WDS) or X-ray diffraction (XRD). ## Crystal Forms It most often occurs as irregular grains intergrown with the host rock (mainly albite). Less commonly, it forms poorly developed, tabular or short prismatic crystals.

Geological environment

## Genesis Lithiotapiolite crystallizes in the final stages of magmatic evolution, in highly differentiated and enriched in rare elements (Li, Cs, Ta, Nb, Sn) granitic pegmatites, referred to as LCT-type pegmatites. ## Mineral Associations This mineral occurs in association with other rare pegmatite minerals, such as wodginite, tantalite-(Mn), tapiolite-(Fe), microlite, simpsonite, as well as more common ones: albite (especially the cleavelandite variety), quartz, spodumene, and lithium micas (lepidolite). ## Localities The type locality and main occurrence of lithiotapiolite worldwide is the Tanco mine, located on Bernic Lake in Manitoba, Canada. This is one of the world's most famous pegmatite deposits rich in tantalum, cesium, and lithium. Beyond this locality, its occurrences are extremely rare.

Rarity

Very rare

For collectors

## Quality Criteria For such a rare mineral, every well-identified specimen is valuable. The most highly prized specimens are those with visible, even if partially formed, crystals, especially if they are embedded in a rock matrix (e.g., on albite) in association with other rare minerals. Crystal size is a key factor influencing value – specimens with crystals exceeding a few millimeters are unique. ## Popular Localities The only source of commercially significant collector specimens is the Tanco mine in Manitoba (Canada). Specimens from this locality set the standard against which all other potential finds are compared.

Care and storage

## Cleaning Lithiotapiolite specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, it can be rinsed with distilled water. Ultrasonic cleaners should be avoided, as they can cause microfractures. ## What to Avoid The mineral is sensitive to strong acids and bases. It should be protected from sudden temperature changes and contact with harder minerals that could scratch it. ## Storage It is recommended to store specimens in separate, padded boxes or display cases to prevent abrasions and mechanical damage. As a stable mineral, it does not require special conditions regarding humidity or light exposure.

Sources

IMA Mineral List (CNMNC)