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.
Description
## Characteristics Suanite is a mineral from the borate group, chemically magnesium borate. It most often occurs in fibrous, radial, or spherulitic aggregates, composed of small, acicular crystals. Less frequently, it forms small, well-formed prismatic crystals. It is usually colorless or white, and can also be pale yellow or pale greenish. Due to its fibrous structure, suanite aggregates may exhibit a delicate, silky luster. ## Physical Properties The Mohs hardness of suanite is 5.5, making it a medium-hard mineral, resistant to scratching by steel. It has a density of approximately 2.91 g/cm³. It exhibits perfect cleavage in one direction. The luster is vitreous on crystal faces and silky on the surfaces of fibrous aggregates. It is a transparent to translucent mineral. ## Colors and Varieties This mineral does not form colored or commercial varieties. Its coloration is usually uniform and includes shades of white, gray, and colorless. Pale yellow or pale green specimens are less common. ## History and Name The name suanite comes from its type locality – the Hol Kol mine in Suan County, North Korea. The mineral was first described by Japanese mineralogist Takeo Watanabe in 1953 based on specimens found in the magnesian skarns there. ## Uses Suanite has no significant industrial use. It is primarily an object of interest for collectors specializing in rare minerals, borates, or skarn minerals, and is also a subject of scientific research.
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
Collector aspects
## 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.