Martyite

Chemical formula: Zn<sup>2+</sup><sub>3</sub>V<sup>5+</sup><sub>2</sub>O<sub>7</sub>(OH)<sub>2</sub>·2H<sub>2</sub>O

Martyite is a very rare, hydrated zinc vanadate, forming characteristic yellow to orange, tabular crystals with a pearly luster.

## Characteristics Martyite is a secondary mineral from the vanadate group, chemically classified as a hydrated zinc divanadate with hydroxyl groups. It occurs as very small, thin, tabular crystals, which often combine into rosette-like or spherical aggregates, and also form coatings and efflorescences. Its most characteristic visual feature is its intense yellow to orange-yellow color and a distinct pearly luster on perfect cleavage surfaces. ## Physical Properties This mineral is relatively soft, with a hardness of about 3 on the Mohs scale. It is brittle and has perfect cleavage in one plane, which causes its crystals to easily separate into thin lamellae. The luster on cleavage surfaces is strongly pearly; on other faces, it can be dull. It is a translucent mineral. Its calculated density is 3.43 g/cm³. ## Colors and Varieties Martyite occurs in shades from bright yellow, through orange-yellow, to brownish-yellow. No named color varieties or commercial varieties are distinguished. ## History and Name Martyite was first described in 1991 by W. S. Wise. Its name honors Joe Marty (born 1945), an American micromineral collector from Utah, who collected the first specimens of this mineral at the Blue Cap mine. The type locality is the Blue Cap mine in the La Sal district, San Juan County, Utah, USA. ## Uses Due to its rarity and occurrence as small crystals, martyite has no industrial applications. It is of purely scientific and collector's interest, being a prized acquisition in micromineral collections.

Properties

Mohs hardness
3
Luster
Pearly, Dull
Streak
Light yellow
Density
3.43
Cleavage
Perfect on {001}
Transparency
Translucent
Crystal system
Orthorhombic

Diagnostic features

## Identification The features facilitating the identification of martyite are its characteristic yellow to orange color, the habit of thin, tabular crystals forming rosettes, and above all, the strong pearly luster on cleavage surfaces. Its occurrence environment – oxidation zones of uranium-vanadium deposits in sandstones – is also of key importance. ## Distinguishing from Similar Minerals Martyite can be confused with other yellow secondary vanadium minerals, such as tyuyamunite, metatyuyamunite, or pascoite. Distinguishing it based on visual features can be difficult and often requires advanced studies, e.g., chemical analysis (EDS) or X-ray diffraction (XRD). Unlike radioactive carnotite, martyite does not exhibit radioactivity. ## Crystal Forms Martyite crystals are thin, tabular or platy, with a micaceous habit. They usually occur in the form of radial aggregates, rosettes, spherulites, or as thin coatings on the host rock.

Geological environment

## Genesis Martyite is a secondary mineral, forming in the oxidation zones of uranium-vanadium deposits that occur in sedimentary rocks, mainly sandstones. It forms as a result of weathering processes and transformations of primary vanadium minerals, such as montroseite. ## Mineral Associations This mineral often co-occurs with other secondary vanadium and uranium minerals. Its most common associations include: volborthite, hewettite, fervanite, tyuyamunite, metatyuyamunite, as well as relics of primary minerals like uraninite and montroseite. ## Localities Martyite is a very rare mineral, known from only a few localities worldwide. The most important and best-documented occurrences are in the USA, on the Colorado Plateau. These include primarily mines in the La Sal district in San Juan County, Utah, including the type locality – the Blue Cap mine, as well as the Packrat mine.

Rarity

Very rare

For collectors

## Quality Criteria The quality of martyite collector specimens is assessed primarily based on the richness and development of the crystals. Specimens with clearly formed, undamaged rosettes of intense, vivid color are most valued. Aesthetic contrast with the color of the host rock and the presence of well-formed crystals of other rare associated minerals enhance its attractiveness. ## Popular Localities The vast majority of the best quality martyite specimens come from its primary localities in Utah, USA, especially from the Blue Cap and Packrat mines in the La Sal district. These are classic and most desired localities for this mineral.

Care and storage

## Cleaning Martyite is a very delicate and sensitive mineral. Only compressed air from a safe distance (photographic blower) should be used to remove dust. Any contact with water should be avoided, as it is a hydrated mineral and can be damaged. ## What to Avoid Water (especially warm water), ultrasonic cleaners, and all chemical agents must be absolutely avoided. The mineral is soft and brittle, so it must be protected from impacts and scratches. Elevated temperatures can lead to dehydration and destruction of the crystal structure. ## Storage Martyite specimens, usually in the form of micromounts, should be stored in closed, padded boxes that protect them from dust, light, and mechanical damage. It is important to ensure stable environmental conditions, without sudden changes in temperature and humidity.

Sources

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