Shuiskite-(Mg)

Chemical formula: Ca₂MgCr³⁺₂(SiO₄)(Si₂O₇)(OH)₂·H₂O

Shuiskite-(Mg) is a rare calcium, magnesium, and chromium silicate, forming small, green crystals in chromite rocks.

## Characteristics Shuiskite-(Mg) is a complex silicate from the sorosilicate group, closely related to shuiskite-(Cr). It occurs as very small, acicular or bladed crystals, rarely exceeding 1 mm in length. It typically forms fibrous aggregates, radial aggregates, or appears as single, disseminated crystals in the host rock. Its intense green color is a characteristic feature, resulting from the presence of chromium in its structure. ## Physical Properties Shuiskite-(Mg) crystals exhibit a vitreous luster. The mineral is translucent to transparent. Due to the small size of the crystals, determining hardness and density is difficult, but they are estimated based on analogies with related minerals. ## Colors and Varieties Shuiskite-(Mg) occurs in shades from emerald-green to dark-green. No color or commercial varieties have been distinguished. ## History and Name The mineral was approved by the IMA in 2001 (IMA2001-026). Its name honors the Russian mineralogist Vitaly Petrovich Shuysky (Виталий Петрович Шуйский, 1937–1996) for his contribution to the study of Ural minerals. The suffix "-(Mg)" distinguishes it from shuiskite-(Cr), where chromium, not magnesium, dominates in a specific structural position. It was first described based on material from the Biserskoye chromite deposit in the Middle Urals, Russia. ## Uses Shuiskite-(Mg) has no industrial applications. It is a mineral of purely scientific and collector's interest, sought after by specialists and advanced collectors of rare minerals.

Properties

Mohs hardness
6
Color
Dark brown with a violet tint
Luster
Vitreous
Streak
light greenish brown
Density
3.24
Cleavage
{001}
Fracture
Uneven
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of shuiskite-(Mg) is based on its characteristic, intensely green color, acicular or bladed crystal habit, and co-occurrence with minerals in chromite rocks. Due to the small size of the crystals, definitive confirmation requires advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS). ## Distinguishing from Similar Minerals Shuiskite-(Mg) can be confused with other green, acicular chromium minerals, such as uvarovite (which is isometric and forms different habits), chromian diopside, or the related shuiskite-(Cr). A certain distinction from shuiskite-(Cr) is only possible through chemical analysis. Its specific occurrence environment distinguishes it from other green minerals. ## Crystal Forms The mineral forms elongated, bladed or acicular crystals, often grouped into radial or fibrous aggregates. Crystals are typically very small, sub-millimeter in size.

Geological environment

## Genesis Shuiskite-(Mg) is a hydrothermal mineral, forming at low temperatures within chromite deposits. It forms in veins cutting chromitites or as an alteration product of primary minerals in serpentinites and other ultramafic rocks. ## Mineral Associations This mineral co-occurs with chromite, calcite, dolomite, uvarovite, chromian diopside, serpentine, chlorite (mainly chromian clinochlore), and other rare chromium minerals. ## Localities The most important and type locality for shuiskite-(Mg) is the Biserskoye (Biser) chromite deposit in the Middle Urals, Russia. It is a very rare mineral, and its occurrence has been confirmed in only a few places worldwide, mainly within ophiolite massifs and chromite deposits.

Rarity

Very rare

For collectors

## Quality Criteria The quality of shuiskite-(Mg) specimens is assessed based on the intensity and saturation of the green color, the size and definition of the crystals, and the richness of their occurrence on the rock matrix. Specimens with well-formed, large (for this mineral) crystals, forming aesthetic, radial aggregates on a contrasting background, are most valued. The absence of damage to the delicate needles is also important. ## Popular Localities The only commercially significant and best-known source of shuiskite-(Mg) specimens is the Biserskoye deposit in the Urals, Russia. Specimens from this locality are considered type examples for this species.

Care and storage

## Cleaning Specimens should only be cleaned mechanically, using a soft brush or compressed air to remove dust. Due to the delicacy of the crystals, contact with water and any chemicals should be avoided. ## What to Avoid Ultrasonic cleaners, acids, detergents, and sudden temperature changes should be absolutely avoided. Brittle crystals are very susceptible to mechanical damage. ## Storage Shuiskite-(Mg) specimens are best stored in enclosed, padded "micromount" boxes to protect them from dust, shocks, and mechanical damage. It is not sensitive to light.

External references

Sources

Read more