Ixiolite-(Mn^2+^)

Chemical formula: (Ta₅+₂/₃Mn₂+₁/₃)O₂

Ixiolite-(Mn) is a rare, black oxide mineral of the ixiolite group, a manganese tantalate, found in granitic pegmatites.

## Characteristics Ixiolite-(Mn) is a rare oxide mineral belonging to the ixiolite group. It occurs as black, opaque, submetallic masses or poorly formed crystals embedded in rock. It typically forms small aggregates, rarely exceeding a few millimeters. Its appearance is inconspicuous, and identification requires advanced analytical methods. ## Physical Properties This mineral is characterized by high hardness, ranging from 6-6.5 on the Mohs scale, and significant density, reaching 7.19 g/cm³. It has a submetallic to metallic luster and a black streak. It is brittle, and its fracture is uneven to conchoidal. It does not exhibit cleavage. ## Colors and Varieties Ixiolite-(Mn) is a mineral of uniform, black color. No color varieties or commercial varieties are known. ## History and Name The name "ixiolite" comes from the discovery locality of the original material in Skogsböle, Finland, in reference to the mythological Ixion, who was bound to a perpetually revolving wheel in Tartarus, alluding to the difficulty in chemically analyzing these complex minerals. The suffix "-(Mn)" indicates the dominance of manganese in the chemical composition of this specific group member. The mineral was formally recognized by the IMA in 2022 as part of the redefinition of the ixiolite group.

Properties

Mohs hardness: 6-6.5
Luster: Sub-metallic
Streak: Black
Density: 7.19
Cleavage: None
Fracture: Uneven to sub-conchoidal
Transparency: Opaque
Crystal system: Orthorhombic

Diagnostic features

## Identification Macroscopic identification of ixiolite-(Mn) is practically impossible. Its black color, submetallic luster, and high density are common features of many heavy metal oxides (e.g., columbite, tantalite). Definitive identification requires advanced analytical techniques, such as X-ray microanalysis (EDS/WDS) to determine chemical composition, especially the tantalum to niobium and manganese ratio. ## Distinguishing from Similar Minerals Ixiolite-(Mn) is most often confused with other black tantalum and niobium minerals, such as tantalite-(Mn), columbite-(Mn), or wodginite. Differentiation from tantalite-(Mn) is based on subtle structural differences that can only be detected by X-ray diffraction (XRD). In collecting practice, without laboratory analysis, these minerals are indistinguishable. ## Crystal Forms Crystals are extremely rare and usually poorly formed, with a tabular or short prismatic habit. Most often, it occurs as irregular, anhedral (unformed) grains and aggregates embedded in quartz or other pegmatite minerals.

Geological environment

## Genesis Ixiolite-(Mn) is an accessory mineral in complex, granitic pegmatites, especially those rich in lithium, cesium, and tantalum (LCT type). It forms in the late stages of pegmatite crystallization, under conditions of high concentration of rare elements such as tantalum and manganese. ## Mineral Associations It most commonly co-occurs with quartz, albite (especially its variety cleavelandite), microcline, lepidolite, elbaite, tantalite-(Mn), wodginite, microlite, and other tantalum minerals. ## Localities Confirmed occurrences of this rare mineral are found in pegmatites worldwide. The most important include: the Tanco mine in Bernic Lake (Manitoba, Canada), pegmatites in the Muiâne region (Zambezia, Mozambique), and in the Viitaniemi area (Orivesi, Finland).

Rarity

Very rare

For collectors

## Quality Criteria The quality of an ixiolite-(Mn) specimen is difficult to assess visually, as its value lies primarily in its laboratory-confirmed identity. For specialized collectors, the most valuable specimens are those with a precisely determined locality (so-called "type locality" or a well-documented occurrence) where the mineral has undergone chemical analysis. The presence of poorly formed crystals, even small ones, significantly increases the value of a specimen compared to amorphous masses. The size of the aggregate and the richness of its association with other rare pegmatite minerals also affect its attractiveness. ## Popular Localities The most sought-after specimens by collectors come from classic localities for rare pegmatite minerals, such as the Tanco mine in Canada and deposits in the Zambezia Province in Mozambique, from which many analyzed and well-described specimens originate.

Care and storage

## Cleaning Due to its rarity and potential brittleness, mechanical cleaning is not recommended. If necessary, compressed air can be used to remove dust. Contact with water or chemicals is inadvisable without absolute necessity. ## What to Avoid Avoid contact with acids and other aggressive chemicals. Due to its brittleness, specimens should be protected from impacts, drops, and vibrations. Ultrasonic cleaning should not be performed. ## Storage Ixiolite-(Mn) specimens should be stored in separate, padded collector boxes to prevent abrasion and mechanical damage. Store in stable conditions, away from moisture and extreme temperatures.