Jinshajiangite

Chemical formula: BaNaFe²⁺₄Ti⁴⁺₂(Si₂O₇)₂O₂(OH)₂F

Jinshajiangite is a rare mineral from the astrophyllite group, forming tabular, reddish-brown crystals with a characteristic lamellar appearance.

## Characteristics Jinshajiangite is a complex silicate of titanium, iron, sodium, and barium, belonging to the astrophyllite supergroup. It forms characteristic thin, tabular or lamellar crystals, often gathered in radial or fan-shaped aggregates. Its appearance is very similar to other minerals in this group, especially astrophyllite, with which it shares a similar structure and crystal habit. ## Physical Properties Jinshajiangite crystals are flexible but not elastic, meaning they can be bent but do not return to their original shape. The mineral exhibits a hardness of approximately 3 on the Mohs scale and a density in the range of 3.55-3.65 g/cm³. The luster is metallic to vitreous, and the mineral is typically translucent to opaque, especially in thicker fragments. ## Colors and Varieties Jinshajiangite occurs in shades from reddish-brown to brownish-red. No named color varieties or commercial varieties are distinguished. ## History and Name The mineral's name comes from the Jinshajiang River (the Chinese name for the upper reaches of the Yangtze River) in Sichuan Province, China, near its type locality. It was described and approved as a new mineral species in 1982. ## Uses Jinshajiangite has no industrial application. However, it is a sought-after and valued collector's stone due to its rarity and attractive forms of occurrence.

Properties

Mohs hardness: 4.5-5
Color: Brown-red, yellow-red, black, black-red
Luster: Vitreous
Streak: Light yellow
Density: 4.2
Cleavage: [010] Perfect, [100] Perfect
Fracture: Uneven
Transparency: Transparent,Translucent
Crystal system: Triclinic

Diagnostic features

## Identification Jinshajiangite is most easily recognized by its characteristic lamellar or tabular crystal habit, often forming radial aggregates. The reddish-brown color, metallic luster, and excellent, unidirectional cleavage are key features. Crystals are flexible but not elastic. ## Distinguishing from Similar Minerals Jinshajiangite is visually almost identical to astrophyllite, which has a similar habit and color (usually more brownish-golden). Definitive differentiation requires advanced chemical analysis (EDS) to confirm the presence of barium, which is a key component of jinshajiangite but not present in astrophyllite. It can also be confused with lamprophyllite, which, however, usually has a lighter, yellowish-brown color. ## Crystal Forms This mineral forms flattened, tabular crystals with a rectangular or lath-like outline. These crystals often arrange themselves into fan-shaped, radial, or star-shaped aggregates, sometimes forming rosettes on the surface of the host rock.

Geological environment

## Genesis Jinshajiangite is an igneous mineral, crystallizing in the late stages from alkaline, silica-undersaturated melts. It occurs mainly in nepheline syenites and associated pegmatites. ## Mineral Associations This mineral often coexists with other minerals typical of alkaline environments, such as aegirine, nepheline, microcline, albite, eudialyte, lorenzenite, and lamprophyllite. ## Localities The most important and well-known localities of jinshajiangite are in Russia on the Kola Peninsula, in the Khibiny and Lovozero alkaline massifs. Most collector specimens originate from there. The mineral also occurs in the Mont Saint-Hilaire igneous complex in Quebec (Canada) and at its type locality in China (Sichuan Province).

Rarity

Rare

For collectors

## Quality Criteria The most valued specimens by collectors are those with well-formed, sharp crystals forming aesthetic, radial or star-shaped aggregates. Color contrast with a light host rock (e.g., white nepheline or albite) is important. Large, undamaged crystal rosettes fetch the highest prices. The luster and intensity of the reddish-brown color also increase the specimen's value. ## Popular Localities By far the most sought-after jinshajiangite specimens come from the alkaline massifs of the Kola Peninsula in Russia. Specimens from Mont Saint-Hilaire in Canada are also valued, but often have smaller crystals.

Care and storage

## Cleaning Specimens should be cleaned only mechanically, using a soft brush to remove dust. If necessary, compressed air can be used. The use of water is not recommended due to its lamellar, delicate structure and the potential presence of unstable associated minerals. ## What to Avoid Contact with acids and other chemicals, which can damage the mineral's surface, should be strictly avoided. Jinshajiangite is brittle and sensitive to impacts and bending. It should not be heated or exposed to prolonged strong sunlight. ## Storage Collector specimens of jinshajiangite, especially those in the form of radial aggregates, are best stored in closed display boxes to protect them from dust and mechanical damage. Due to its brittleness, it is not suitable for mounting in jewelry.