Yuksporite

Chemical formula: K<sub>4</sub>(Ca,Na)<sub>14</sub>(Sr,Ba)<sub>2</sub>(&#9744;,Mn<sup>2+</sup>,Fe<sup>3+</sup>)(Ti<sup>4+</sup>,Nb<sup>5+</sup>)<sub>4</sub>(O,OH)<sub>4</sub>(Si<sub>6</sub>O<sub>17</sub>)<sub>2</sub>(Si<sub>2</sub>O<sub>7</sub>)<sub>3</sub>(H<sub>2</sub>O,OH)<sub>3</sub>

Yuksporite is a rare silicate with a complex chemical composition, forming fibrous or lamellar aggregates with a silky luster and pink, yellow, or brown color.

## Characteristics Yuksporite is a complex inosilicate mineral from the umbite group, found in ultra-alkaline rock massifs. It forms characteristic aggregates with a radiating-fibrous, tangled-fibrous, lamellar, or granular structure. Well-formed crystals are extremely rare. Its appearance is very distinctive, and specimens often exhibit a silky luster on the surfaces of the fibers. ## Physical Properties This mineral is characterized by a hardness of approximately 5 on the Mohs scale. It has a silky luster, and a vitreous luster on fresh fractures. It is a translucent mineral, rarely opaque. Its density ranges from 2.83 to 3.05 g/cm³. ## Colors and Varieties Yuksporite most commonly ranges in color from pink and pinkish-yellow to reddish-brown. Pale yellow or almost colorless specimens are also found. No named varieties of this mineral are distinguished. ## History and Name The mineral's name, given in 1923 by Alexander Fersman, comes from its discovery location – Mount Yukspor (Yukspor) in the Khibiny Massif on the Kola Peninsula in Russia. This is its type locality. ## Uses Yuksporite has no industrial application. It is valued solely as a collector's stone due to its rarity, attractive structure, and limited occurrence.

Properties

Mohs hardness
5
Luster
Silky, Vitreous
Streak
White
Density
2.83-3.05
Cleavage
Good on {100} and {001}
Fracture
Uneven
Transparency
Translucent to opaque
Crystal system
Monoclinic

Diagnostic features

## Identification Yuksporite is most easily recognized by its characteristic radiating-fibrous or tangled structure and silky luster. The pink or yellowish-brown color, combined with its occurrence in alkaline nepheline pegmatites, is a strong diagnostic indicator. ## Distinguishing from Similar Minerals Yuksporite is sometimes confused with other fibrous minerals from Khibiny, such as tinaksite or charoite (although charoite has a different, purple color and comes from a different massif). From tinaksite, which often co-occurs and has a similar habit, it is usually distinguished by a more pinkish hue (tinaksite is more often orange-brown) and the absence of the pleochroism characteristic of tinaksite. However, definitive differentiation requires advanced analysis, e.g., XRD. ## Crystal Forms Crystals are extremely rare and have a platy or bladed habit. It usually forms radiating-fibrous, tangled-fibrous, lamellar aggregates, as well as massive, granular groupings.

Geological environment

## Genesis Yuksporite is a hydrothermal mineral, typical of highly alkaline, differentiated intrusive complexes. It forms in pegmatites and hydrothermal veins cutting nepheline syenites and associated rocks. ## Mineral Associations This mineral often co-occurs with other rare minerals of alkaline pegmatites. Its most common associations include: microcline, nepheline, aegirine, lamprophyllite, eudialyte, titanite, pectolite, as well as tinaksite, rasvumite, and wadeite. ## Localities The most important and globally renowned yuksporite localities are in Russia, within the alkaline massifs on the Kola Peninsula. These are primarily the Khibiny Massif (Mount Yukspor, Eveslogchorr, Rasvumchorr) and, to a lesser extent, the Lovozero Massif. Outside Russia, its occurrence has been reported in Canada (Mont Saint-Hilaire, Quebec).

Rarity

Rare

For collectors

## Quality Criteria The most prized specimens by collectors are those with well-formed, radiating aggregates of intense pink color and strong silky luster. Large, rich groupings of yuksporite embedded in the host rock (matrix), often accompanied by other rare minerals from Khibiny (e.g., eudialyte), fetch higher prices. Clarity is not a key criterion; the form and aesthetics of the aggregate are what matter. ## Popular Localities By far the most sought-after specimens come from the type locality – the Khibiny Massif on the Kola Peninsula in Russia. Material from this region is considered classic and serves as the benchmark for this mineral.

Care and storage

## Cleaning Yuksporite specimens should be cleaned very carefully, using a soft brush to remove dust. Compressed air can be used. Due to its fibrous nature, washing in water, especially under pressure, is not recommended, as it can damage delicate aggregates. If liquid is necessary, distilled water and very gentle drying are advised. ## What to Avoid Avoid contact with acids and strong chemicals, which can react with the mineral's complex composition. Do not clean it with ultrasonics. Although not particularly sensitive to light, prolonged exposure to direct sunlight may not be advisable. It is brittle and sensitive to impacts. ## Storage It is recommended to store specimens in closed boxes or display cases to protect them from dust and mechanical damage. Delicate, fibrous aggregates require special care and should be placed on a soft surface, away from vibrations.

External references

Sources

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