Zhemchuzhnikovite
Chemical formula: NaMgAl((C<sub>2</sub>)<sup>6+</sup>O<sub>4</sub>)<sub>3</sub>·9H<sub>2</sub>O
Zhemchuzhnikovite is a very rare, water-soluble organic mineral, forming green, prismatic crystals.
Properties
- Mohs hardness
- 2
- Luster
- Vitreous
- Streak
- White
- Density
- 1.56
- Cleavage
- Perfect on {0001}
- Fracture
- Conchoidal
- Transparency
- Transparent
- Crystal system
- Trigonal
Diagnostic features
## Identification The key diagnostic features are its apple-green color, hexagonal crystal shape, and immediate reaction to contact with water (dissolution). A white streak and low hardness are also helpful in identification. ## Distinguishing from similar minerals No other mineral of similar appearance exhibits such rapid water solubility. It can be confused with other green, secondary minerals formed in mines, but the water drop test is decisive and unambiguously identifies it (though it destroys a fragment of the specimen). ## Crystal forms The mineral forms hexagonal, prismatic crystals, often terminated by a pyramid. It occurs as single, well-formed crystals or small, loose accumulations thereof.
Geological environment
## Genesis Zhemchuzhnikovite is a secondary mineral, formed under specific conditions within brown coal deposits. Its formation results from the interaction of oxalate-rich solutions (derived from the decomposition of organic matter) with waters containing sodium, magnesium, and aluminum, released from the rocks surrounding the deposit. It forms under low-temperature conditions, often in voids and fractures. ## Mineral associations It co-occurs with other rare oxalates, such as stepanovite, and with minerals typical of coal deposit environments, such as gypsum, calcite, or sulfur. ## Localities The only confirmed and well-documented occurrence of this mineral in the world is its type locality – the "Tsvetnoi" brown coal mine in the Dnieper basin, near Oleksandriia, Ukraine.
Rarity
Extremely rare
For collectors
## Quality criteria The quality of a zhemchuzhnikovite specimen is primarily assessed based on the size, form, and transparency of the crystal. The most valued are single, sharply terminated, fully transparent crystals with an intense, apple-green color. Minimal mechanical damage is also important. Due to its instability, specimens preserved in paraffin oil or other protective media are standard and do not diminish their value. ## Popular localities The only source of collector specimens is the historical type locality in Ukraine. All specimens available on the market originate from this single location.
Care and storage
## Cleaning This mineral must absolutely not be wet cleaned. Any contact with water, even in the form of water vapor, leads to its dissolution and destruction. Specimens are not cleaned. ## What to avoid Avoid water, high humidity, alcohol, and all other liquids. The mineral is very soft and brittle, so avoid any mechanical pressure, friction, or impact. Store away from heat sources. ## Storage Zhemchuzhnikovite specimens require storage in hermetically sealed containers, preferably with a desiccant (e.g., silica gel). The safest method is to immerse the crystal in an anhydrous, chemically inert liquid, such as paraffin oil, which protects it from air and moisture. Display should only take place in sealed display cases or "perky boxes."