Mathewrogersite

Chemical formula: Pb₂+₇Fe₂+Al₃GeSi₁₂O₃₆(OH,H₂O)₆

Mathewrogersite is a very rare, hydrated lead, iron, aluminum, and germanium silicate, forming hexagonal, tabular, yellow crystals.

## Characteristics Mathewrogersite is a mineral from the silicate group, distinguished by its complex chemical composition, including lead, iron, aluminum, germanium, and silicon. It occurs as small, hexagonal crystals with a tabular habit, often forming rosette-like or spherical aggregates. Its typical specimens are small, rarely exceeding 1 mm, and are characterized by a light yellow to yellowish-green color. ## Physical Properties Mathewrogersite crystals exhibit a vitreous luster. The mineral's hardness on the Mohs scale is approximately 3. It is a relatively heavy mineral due to its high lead content, and its calculated density is 4.85 g/cm³. It is transparent to translucent. ## Colors and Varieties This mineral occurs in shades from light yellow to yellowish-green. No varieties have been distinguished. ## History and Name Mathewrogersite was first described in 1985 by P.J. Dunn, D.R. Peacor, S.-C. Su, J.A. Nielen, and D.E. Ramik. The mineral's name honors Mathew Rogers (born 1951), an American mineral collector from Medina, Ohio, who provided samples for study. ## Uses Due to its extreme rarity and microscopic crystal sizes, mathewrogersite has no industrial applications. It is solely an object of scientific and collecting interest for specialized collectors of rare minerals.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: Pale yellow
Density: 4.85
Cleavage: Perfect on {0001}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Hexagonal

Diagnostic features

## Identification Mathewrogersite is identified by its unique appearance: small, yellow, hexagonal, tabular crystals, often in rosette-like aggregates. Its occurrence in a specific geological environment in the Tsumeb mine, in paragenesis with other rare germanium minerals, is key. ## Distinguishing from Similar Minerals It can be confused with other rare, yellow secondary minerals from Tsumeb, such as stottite, itoigawaite, or some arsenates. Definitive distinction requires advanced analytical methods, such as chemical analysis (EDS) to confirm the presence of lead, aluminum, iron, and germanium, and X-ray diffraction (XRD). ## Crystal Forms Crystals are hexagonal, thin-tabular, often arranged in rosettes or spherical aggregates. Bladed forms are also observed.

Geological environment

## Genesis Mathewrogersite is a secondary mineral that formed in the oxidation zone of a mineralized, dolomitic polymetallic deposit. Its crystallization occurred at low temperatures from hydrothermal solutions rich in germanium, which interacted with earlier sulfides. ## Mineral Associations This mineral co-occurs with other rare minerals, especially those containing germanium. In its type locality (Tsumeb), it was found in association with quartz, galena, tennantite, germanite, stottite, and brunogeierite. ## Localities The only confirmed occurrence of mathewrogersite in the world is the Tsumeb mine in the Oshikoto Region, Namibia. This is its type locality.

Rarity

Extremely rare

For collectors

## Quality Criteria The most prized mathewrogersite specimens are those with sharp, well-formed crystals creating aesthetic, rosette-like aggregates. An intense, light yellow color and contrast with the host rock (matrix) are important. Due to the microscopic size of the crystals, specimens are evaluated under magnification. Any aggregate visible to the naked eye is already an exceptional specimen. ## Popular Localities The only source of mathewrogersite specimens is historical collections originating from the Tsumeb mine in Namibia. This mine is currently closed, meaning no new specimens are entering the market.

Care and storage

## Cleaning Mathewrogersite specimens are extremely delicate and small. Mechanical cleaning is not recommended. If absolutely necessary, compressed air (from a safe distance) can be used to remove loose dust. Avoid contact with water and any chemicals. ## What to Avoid Ultrasonic cleaners, steam cleaners, acids, solvents, and sudden temperature changes should be strictly avoided. The mineral is soft and easily susceptible to mechanical damage. As a lead-containing silicate, it may be sensitive to certain chemical agents. ## Storage Specimens should be stored under stable conditions, in sealed "micromount" boxes, to protect them from dust, physical damage, and humidity. Store away from direct sunlight and heat sources.

Sources

IMA Mineral List (CNMNC)