Rüdlingerite

Chemical formula: Mn₂+₂V₅+As₅+O₇·₂H₂O

Rüdlingerite is an extremely rare, hydrated manganese vanadate-arsenate, forming microscopic crystals of intense, yellowish-orange color.

## Characteristics Rüdlingerite is a mineral from the vanadate and arsenate group, chemically classified as a hydrated manganese vanadate-arsenate. It occurs as very small, bladed or tabular crystals, rarely exceeding 0.2 mm in length. These crystals often form radial or sub-parallel aggregates. A characteristic feature of the mineral is its vivid, intense color, ranging from yellowish-orange to brownish-orange. ## Physical Properties This mineral is relatively soft, with a hardness of about 3 on the Mohs scale. It has a vitreous luster, sometimes transitioning to greasy. It is translucent. Its density, calculated based on the chemical formula and unit cell parameters, is approximately 3.75 g/cm³. ## Colors and Varieties The dominant and only known color of rüdlingerite is an intense yellowish-orange, which can transition to brownish hues. No color varieties or commercial varieties have been distinguished. ## History and Name The mineral was recognized by the International Mineralogical Association (IMA) in 2002. Its name comes from the discovery locality – the Rüdlinger quarry in the Klettgau valley, Schaffhausen canton, Switzerland. It was described by a team of mineralogists: Nicolas Meisser, Joël Brugger, Stefan Ansermet, Pierre Perroud, and Eric Reusser. ## Applications Due to its extreme rarity and microscopic crystal size, rüdlingerite has no industrial application. It is solely an object of scientific interest and a valuable acquisition for specialized collectors of rare minerals (so-called microminerals).

Properties

Mohs hardness: 3
Luster: Vitreous to greasy
Streak: Light yellow
Density: 3.75
Cleavage: Good on {010}
Fracture: Uneven
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Amateur identification of rüdlingerite is practically impossible. Key visual features include its characteristic yellowish-orange color, bladed form of microscopic crystals, and specific occurrence environment. Definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS), which can confirm its unique chemical composition with the simultaneous presence of vanadium and arsenic. ## Distinguishing from Similar Minerals Rüdlingerite can be confused with other rare, secondary manganese minerals of similar color, such as some arsenates or vanadates. Final differentiation from minerals such as ansermetite or medaite, with which it co-occurs, is only possible based on detailed laboratory analyses. ## Crystal Forms Rüdlingerite crystals have a bladed or thin-tabular habit. They usually occur as small, individual crystals or form fan-shaped, radial, and sub-parallel aggregates on the surface of the host rock.

Geological environment

## Genesis Rüdlingerite is a secondary mineral. It forms as a result of low-temperature hydrothermal processes or weathering occurring within manganese deposits. In its type locality (Rüdlinger quarry), it occurs in fractures of Triassic dolomitic rocks containing manganese mineralization. ## Mineral Associations This mineral occurs in association with other, often rare, manganese minerals. The most common associations include: ansermetite, medaite, piedmontite, todorokite, quartz, and manganocalcite. ## Localities It is an extremely rare mineral, known from only a few localities worldwide. The most important and confirmed occurrences are in Switzerland: - Rüdlinger quarry, Klettgau, Schaffhausen (type locality). - Falotta and Starlera manganese mines, Oberhalbstein, Graubünden.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of rüdlingerite specimens, being a typical micromineral, is assessed according to different criteria than for macroscopic minerals. Specimens with well-formed, sharp crystals, even if they are fractions of a millimeter in size, are most highly valued. The intensity and purity of the color, the richness of occurrence on the rock matrix, and the aesthetic arrangement of aggregates are important. Association with other rare minerals also enhances its attractiveness. ## Popular Localities All known collector specimens come from Switzerland. The best are considered to be those from the type locality in the Rüdlinger quarry and from the historical manganese mines of Falotta and Starlera in Graubünden, from where rich microscopic samples originate.

Care and storage

## Cleaning Rüdlingerite specimens should be cleaned with the utmost care, preferably using a soft brush to remove dust. Due to the presence of water in its structure and potential reactivity, contact with water and any chemicals should be avoided. If liquid is necessary, isopropyl alcohol can be very carefully applied with a cotton swab, avoiding oversaturation of the specimen. ## What to Avoid The mineral is soft and brittle, so it should be protected from impacts and scratches. Exposure to high temperatures, which can cause dehydration and destruction of the crystal structure, should be avoided. Also avoid ultrasonics, acids, detergents, and prolonged exposure to strong light. ## Storage The safest way to store rüdlingerite is to place it in a specialized micromount box, which protects the specimen from dust, moisture, and mechanical damage. Store in stable room conditions.

Sources

IMA Mineral List (CNMNC)