Buserite
Chemical formula: Na<sub>4</sub>Mn<sup>3+</sup><sub>6</sub>Mn<sup>4+</sup><sub>8</sub>O<sub>27</sub>·21H<sub>2</sub>O
A historical, discredited name for a group of synthetic and natural hydrated manganese oxides that do not constitute a distinct mineral species.
Description
## Characteristics Buserite is not a recognized, distinct mineral, and its name has been officially discredited by the International Mineralogical Association (IMA). Historically, this term referred to synthetic or natural, hydrated manganese oxides with a characteristic layered structure and an interlayer spacing of approximately 10 angstroms (10Å). These materials occur as very fine-grained, earthy or sooty aggregates of black or brownish-black color and a dull luster. ## Physical Properties Since buserite is not a defined mineral, its physical properties are variable. Aggregates are typically very soft and light, with low density, due to their porous structure and high water content. They easily smudge fingers when touched. ## Colors and Varieties The described materials are uniformly black, less commonly dark brown. No varieties are distinguished in a mineralogical sense. ## History and Name The name was given in honor of the Swiss chemist Werner Buser, who first synthesized and described this phase in the 1950s. Later studies showed that natural substances referred to as buserite are actually other manganese minerals, such as todorokite or birnessite, or their mixtures. Synthetic buserite proved to be unstable and readily dehydrates to birnessite. For these reasons, the name has been discredited and should not be used to describe natural minerals.
Diagnostic features
## Identification Identification of materials historically called buserite is impossible without advanced analytical techniques, primarily X-ray diffraction (XRD), which allows for the determination of the crystal structure and actual mineral affiliation (e.g., to todorokite or birnessite). Visually, they are indistinguishable from other manganese oxides. ## Distinguishing from similar minerals They can be confused with a whole group of black, earthy manganese oxides collectively referred to as "wad," as well as with pyrolusite, birnessite, todorokite, cryptomelane, or hollandite. Differentiation based on external features is not possible. ## Crystal forms It does not form crystals visible to the naked eye. It occurs exclusively in the form of very fine-grained, sooty, powdery, or earthy aggregates and crusts.
Geological environment
## Genesis Manganese phases of this type form in low-temperature, oxidizing aqueous environments. They precipitate from seawater as a main component of deep-sea manganese nodules and crusts. They also occur on land as products of weathering of other manganese minerals and in lake and bog sediments. ## Mineral associations They co-occur with other manganese oxides and hydroxides (todorokite, birnessite, rancieite, pyrolusite, cryptomelane) and iron (goethite, ferrihydrite). ## Localities The term "buserite" was historically associated with material from deep-sea manganese nodules from the Pacific Ocean floor. Since the name is discredited, there are no official localities for the occurrence of this "mineral."
Rarity
Discredited
Collector aspects
## Quality criteria Buserite is not a mineral in the formal sense and is not of interest to collectors. Specimens containing phases formerly referred to by this name (e.g., fragments of manganese concretions) have only scientific and study value. ## Market prices There is no collector's market and associated prices. ## Popular localities There are no localities valued by collectors.
Care and storage
## Cleaning Not applicable, the material is not a collector's item. Research specimens are extremely delicate and brittle, disintegrating upon contact with water. ## What to avoid Avoid contact with water, chemicals, and any mechanical stress that could damage the sample. ## Storage Research samples require storage in sealed, stable containers that protect against moisture and mechanical damage.