Melansonite
Chemical formula: Na◻₂KZr⁴⁺Si₈O₁₉(H₂O)₅
Melansonite is a newly discovered, hydrated sodium, potassium, and zirconium silicate, forming colorless, tabular crystals with a pearly luster.
Properties
- Mohs hardness
- 3-4
- Color
- colorless to pale yellow
- Luster
- Pearly
- Streak
- white
- Density
- 2.352
- Cleavage
- {100}
- Fracture
- Irregular/Uneven
- Transparency
- Transparent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identification of melansonite is possible only through advanced analytical methods, such as X-ray diffraction (XRD) and chemical analysis (EDS/WDS). Visual identification in the field or even in a collection is impossible due to its microscopic size and similarity to many other silicates. ## Distinguishing from similar minerals Melansonite can be confused with other colorless, white, or gray minerals found at Mont Saint-Hilaire, such as analcime, natrolite, eudialyte, or serandite. Differentiation requires specialized laboratory equipment. ## Crystal forms Melansonite crystals are tabular, flattened parallel to the {001} plane, and have a hexagonal or pseudohexagonal outline. They typically form rosette-like or spherical aggregates up to 0.5 mm in diameter.
Geological environment
## Genesis Melansonite occurs in syenite pegmatites that have undergone alteration during the late stage of hydrothermal processes. It forms in cavities and rock fractures within these complex alkaline intrusions. ## Mineral associations This mineral coexists with many other rare minerals typical of the Mont Saint-Hilaire locality. The most common associations include analcime, aegirine, microcline, natrolite, serandite, and eudialyte. ## Localities The only confirmed locality for melansonite in the world is the Poudrette quarry, located on Mont Saint-Hilaire, in the Montérégie region, Quebec province, Canada.
Rarity
Extremely rare
For collectors
## Quality criteria As a "micromount" mineral, the collector's value of melansonite depends on the quality and size of the crystal aggregates, as well as the aesthetics of the associated minerals. The most desirable specimens are well-formed, sharp, and undamaged crystal rosettes, clearly contrasting with the rock matrix. Due to its extreme rarity, any specimen with confirmed identification is extremely valuable. ## Popular occurrences The only source of melansonite specimens is its type locality – the Poudrette quarry in Mont Saint-Hilaire, Canada, world-renowned for hundreds of unique and rare mineral species.
Care and storage
## Cleaning Due to its extreme rarity, small crystal size, and delicacy, melansonite specimens should not undergo standard cleaning. Any procedures should be performed exclusively by specialists under laboratory conditions. ## What to avoid Avoid contact with chemicals, ultrasound, steam, and any mechanical tools. The mineral is soft and brittle, and its stability under various conditions is not fully understood. It should be protected from changes in temperature and humidity. ## Storage Melansonite specimens should be stored under stable conditions, preferably in specialized, padded "micromount" boxes, protecting them from dust, vibrations, and mechanical damage. Avoid exposure to direct sunlight.