Sørensenite
Chemical formula: Na₄Be₂Sn⁴⁺(Si₃O₉)₂·2H₂O
Sørensenite is a rare sodium, beryllium, and tin silicate, forming colorless or pink, tabular crystals, discovered in Greenland.
Properties
- Mohs hardness
- 5.5
- Luster
- Vitreous
- Streak
- White
- Density
- 2.9
- Cleavage
- On <mi>{10_1}</mi> and {100}. The angle <mi>(10_1)</mi> ∧ (100) = 63°.
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Sørensenite can be identified by its characteristic, tabular or bladed crystals, often forming radial aggregates. Its colorless or pinkish color, vitreous luster, and occurrence in a specific geological environment (nepheline-sodalite pegmatites) are key features. ## Distinguishing from similar minerals It can be confused with other colorless or white silicates found in the same environment, such as natrolite or analcime. However, it is distinguished by its higher hardness (5.5) and unique crystal and aggregate forms. Final confirmation requires advanced analytical methods, such as X-ray diffraction (XRD). ## Crystal Forms Crystals are typically tabular or bladed, elongated and flattened. They often form fan-shaped, radial, or even spherical aggregates, which are very characteristic of this mineral.
Geological environment
## Genesis Sørensenite is a hydrothermal mineral, crystallizing in the late stage of evolution of agpaitic pegmatites (strongly alkaline, sodium-rich, and silica-poor). It forms in vugs and fissures within nepheline-sodalite rocks. ## Mineral Associations This mineral co-occurs with other rare alkaline minerals, such as aegirine, analcime, arfvedsonite, microcline, nepheline, sodalite, eudialyte, steenstrupine-(Ce), chkalovite, and ussingite. ## Localities The most important and classic localities for sørensenite are in the Ilímaussaq alkaline complex in Greenland, particularly on Nakkaalaaq mountain and the Kuannersuit (Kvanefjeld) plateau. Outside Greenland, its occurrence has also been reported in the Lovozero Massif on the Kola Peninsula in Russia.
Rarity
Very rare
For collectors
## Quality Criteria The most valued by collectors are specimens with well-formed, sharp, and undamaged crystals, forming aesthetic, radial aggregates. Transparency and a delicate, pink color are important. Specimens on matrix, contrasting with other associated minerals (e.g., dark aegirine), are particularly sought after. ## Popular Localities By far the best and most famous specimens come from the type locality - the Ilímaussaq complex in Greenland. Material from the Kola Peninsula is usually less spectacular and less common on the collector's market.
Care and storage
## Cleaning Sørensenite 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 dry the specimen thoroughly after cleaning. ## What to avoid Avoid contact with acids and other aggressive chemicals. The mineral is brittle, so it must be protected from impacts and falls. It should not be cleaned in ultrasonic cleaners. ## Storage It is recommended to store sørensenite in a separate, padded display box to avoid scratches from harder minerals and protect it from mechanical damage. It is not sensitive to light, but should be protected from dust and moisture.