Steedeite
Chemical formula: NaMn²⁺₂[Si₃BO₉](OH)₂
Steedeite is a rare sodium manganese borosilicate, discovered at Mont Saint-Hilaire in Canada, forming colorless or pale pink crystals.
Properties
- Mohs hardness
- 5
- Luster
- Vitreous
- Streak
- White
- Density
- 3.106
- Cleavage
- None
- Fracture
- Irregular/Uneven
- Transparency
- Transparent,Translucent
- Crystal system
- Triclinic
Diagnostic features
## Identification Steedeite is difficult to identify visually without specialized equipment. Its characteristic features include its occurrence as small, tabular crystals, often forming radial aggregates, pale pink or colorless hue, and vitreous luster. Crucial for identification is its specific geological environment at Mont Saint-Hilaire. ## Distinguishing from Similar Minerals It can be confused with other rare silicates from Mont Saint-Hilaire, such as serandite or leucophanite. Final distinction requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS), due to similar appearance and co-occurrence with many other minerals. ## Crystal Forms Steedeite crystals are typically very small, with a tabular or bladed habit. They often occur in radial or rosette-like aggregates, intergrown with other minerals.
Geological environment
## Genesis Steedeite forms in the late stages of crystallization within syenite xenoliths and hornfelses that have been altered by hydrothermal processes. It is a product of the activity of rare-element-rich solutions, including boron, in the unique environment of the Mont Saint-Hilaire alkaline intrusive complex. ## Mineral Associations This mineral co-occurs with many other rare minerals from Mont Saint-Hilaire. It is most often found in association with analcime, aegirine, microcline, nepheline, sodalite, eudialyte, serandite, polylithionite, and leucophanite. ## Localities The only confirmed and described locality for steedeite in the world is its type locality – the Poudrette quarry at Mont Saint-Hilaire, in the Montérégie region, Quebec province, Canada. This is one of the most famous mineralogical sites in the world, known for the occurrence of hundreds of unique mineral species.
Rarity
Extremely rare
For collectors
## Quality Criteria The most prized steedeite specimens are those with well-formed, sharp crystals of a distinct, pale pink color, forming aesthetic, radial aggregates. Due to the small size of the crystals, their quality and form are crucial. Contrast with associated minerals (matrix), for example with white analcime, also increases the collectible value of the specimen. ## Popular Localities The only source of steedeite specimens is the Poudrette quarry at Mont Saint-Hilaire, Canada. Specimens from this locality are highly sought after by collectors specializing in rare minerals and minerals from this specific locality.
Care and storage
## Cleaning Steedeite specimens should be cleaned very carefully, using a soft brush to remove dust. If necessary, distilled water can be used, but prolonged soaking should be avoided. Always thoroughly dry the specimen after cleaning. ## What to Avoid Avoid contact with acids and other aggressive chemicals that can damage the mineral. It should not be cleaned in ultrasonic cleaners. Due to its moderate hardness, it is susceptible to scratches, so it should be protected from contact with harder minerals. ## Storage Steedeite specimens, being extremely rare and usually small, are best stored in specialized display boxes or cabinets, away from dust and direct sunlight. It is advisable to isolate it from other minerals to prevent mechanical damage.