Suanite
Chemical formula: Mg<sub>2</sub>B<sub>2</sub>O<sub>5</sub>
Suanite is a magnesium borate, most commonly forming fibrous or radial aggregates in magnesian skarns.
Properties
- Mohs hardness
- 5.5
- Luster
- Vitreous to Silky
- Streak
- White
- Density
- 2.91
- Cleavage
- Perfect on {100}, Good on {010}
- Fracture
- Uneven
- Transparency
- Transparent to Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification A characteristic feature of suanite is its occurrence in the form of white, fibrous or radial aggregates. Key to identification is its environment of occurrence – magnesian skarns, where it coexists with other borates and metamorphic minerals. The silky luster in fibrous aggregates is also a helpful clue. ## Distinguishing from Similar Minerals Suanite is sometimes confused with szaibelyite, another magnesium borate, which often coexists with it. Szaibelyite, however, is much softer (hardness 3-3.5). It may also resemble fibrous silicates, such as tremolite or wollastonite. Final and certain differentiation of these minerals usually requires advanced research methods, such as X-ray diffraction (XRD). ## Crystal Forms Suanite crystallizes in the monoclinic system. The most common forms are fibrous, radial, and spherulitic aggregates. Well-formed, single crystals are rare and usually appear as short, tabular or prismatic columns.
Geological environment
## Genesis Suanite is a mineral typical of contact metamorphism processes. It forms at high temperatures in contact zones of granitoid intrusions with sedimentary carbonate rocks rich in magnesium (dolomites or dolomitic limestones). Under such conditions, so-called magnesian skarns, enriched in boron, are formed. ## Mineral Associations This mineral often coexists with other magnesium borates, such as kotoite, ludwigite, and szaibelyite. It is also accompanied by skarn minerals, including forsterite (olivine), clinohumite, spinel, magnetite, fluorite, calcite, and dolomite. ## Localities The most important suanite localities in the world include its type locality in Suan, North Korea. It is also known from many boron deposits in Russia (e.g., in Siberia and the Urals), from Crestmore, California (USA), from the Kilmar mine in Cornwall (United Kingdom), and from several locations in Japan and China.
Rarity
Not very common
For collectors
## Quality Criteria The most highly valued by collectors are specimens with well-formed, visible-to-the-naked-eye crystals, which are, however, very rare. Aesthetic, pure white aggregates with a radial or spherulitic structure, contrasting with the host rock, are also very popular. The purity of the specimen and the absence of damage to delicate, fibrous structures are important. ## Popular Localities Specimens from the classic locality in North Korea are of historical significance but are practically unavailable on the market. Good quality collector material mainly comes from skarns in Russia and from the historical locality in Crestmore, California.
Care and storage
## Cleaning Suanite specimens should only be cleaned with distilled water and a soft brush. Due to their fibrous nature, aggregates can be brittle and prone to disintegration, so strong rubbing should be avoided. Ultrasonic cleaners are not recommended. ## What to Avoid Contact with acids, which can react with the mineral, should be avoided. A hardness of 5.5 on the Mohs scale means it can be scratched by harder minerals (e.g., quartz), so it should be protected from contact with them. It is not sensitive to light or temperature changes under household conditions. ## Storage It is recommended to store suanite specimens in separate, sealed boxes or display cases to avoid scratches and mechanical damage. Delicate, fibrous aggregates should be protected from shocks and pressure.