Magganasite
Chemical formula: Cu<sup>2+</sup>Fe<sup>3+</sup><sub>3</sub>O(As<sup>5+</sup>O<sub>4</sub>)<sub>3</sub>
Magganasite is an extremely rare copper and iron arsenate, forming black, tabular crystals in small rosettes.
Description
## Characteristics Magganasite is a very rare mineral from the arsenate group, with a complex chemical composition containing copper and iron. It occurs as very small, black, opaque crystals with a submetallic luster. Typical specimens form aggregates of thin, tabular or platy crystals, which often arrange themselves into rosette-like forms or spherical clusters. The size of individual crystals rarely exceeds 0.2 mm, making it a mineral primarily available to collectors specializing in microminerals. ## Physical Properties The luster of magganasite is described as submetallic. It is an opaque mineral. Its hardness has not yet been precisely determined. The density, calculated based on its chemical composition and unit cell parameters, is 4.61 g/cm³. ## Colors and Varieties This mineral occurs exclusively in black. No color varieties or commercial varieties are known. ## History and Name Magganasite was officially described as a new mineral species in 2012 by a team of mineralogists led by Nikita V. Chukanov. Its name comes from the Maggana area, located near the discovery site in the Lavrion (Laurion) district of Greece. The mineral was approved by the International Mineralogical Association (IMA). ## Uses Due to its extreme rarity and occurrence as microscopic crystals, magganasite has no industrial application. It has only scientific and collectible significance, being an object of desire among specialized collectors of rare minerals.
Diagnostic features
## Identification Identification of magganasite is based on its unique visual characteristics at the micro scale. Characteristic features include aggregates of black, submetallic, tabular crystals forming rosette-like shapes. A key diagnostic clue is the location (Lavrion, Greece) and co-occurrence with goethite and quartz. Definitive identification is only possible using advanced analytical techniques, such as X-ray diffraction (XRD) or energy-dispersive X-ray spectroscopy (EDS). ## Distinguishing from Similar Minerals It can be confused with other black, microcrystalline secondary minerals from Lavrion, especially other rare arsenates. Distinguishing it "by eye" from similar minerals without analytical confirmation is practically impossible. ## Crystal Forms It forms thin, tabular or platy crystals with a hexagonal outline. These crystals almost always occur as radial or spherical aggregates and rosettes.
Geological environment
## Genesis Magganasite is a secondary mineral that forms under specific weathering conditions. It originates in voids within ancient, remelted mining slags that have undergone natural hydrothermal processes and oxidation for hundreds of years. Its host rock is a compact goethite-quartz mass. ## Mineral Associations This mineral occurs in direct association with goethite and quartz. ## Localities The only confirmed locality of magganasite in the world is its type locality - the "Maria" vein in the Kamariza mines area, in Agios Konstantinos, Lavrion (Laurion) district, Attica, Greece.
Rarity
Extremely rare
Collector aspects
## Quality Criteria The quality of magganasite specimens, being a micromineral, is assessed by different criteria than for macroscopic specimens. Specimens with well-formed, sharp, and undamaged crystals forming aesthetic rosettes are most highly valued. The "richness" of the specimen, i.e., the number and size of aggregates on the rock matrix, is also important. Contrast with a light quartz matrix can enhance visual appeal. ## Popular Localities The only source for obtaining specimens is the historic mining region of Lavrion in Greece. Specimens from this locality are the standard for this mineral.
Care and storage
## Cleaning Magganasite specimens are extremely delicate and small. Mechanical cleaning with brushes or needles is strongly discouraged. Ultrasonic cleaners should not be used. If necessary, dust can be removed with a very gentle stream of compressed air from a safe distance. ## What to Avoid Contact with all chemicals, especially acids, which can destroy the mineral, should be avoided. As an arsenate, it should be stored away from moisture. It should be protected from abrasion and impact. ## Storage It is recommended to store specimens exclusively in specialized, sealed micromount boxes, which protect them from dust, moisture, and mechanical damage. Each specimen should be precisely labeled.