Delrioite

Chemical formula: Sr(V<sup>5+</sup>O<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O

Delrioite is a rare, hydrated strontium vanadate, forming aggregates of tiny, yellowish-green crystals.

## Characteristics Delrioite is a rare mineral from the vanadate group. It occurs as aggregates of very small, platy or fibrous crystals, rarely exceeding 1 mm in length. It also forms coatings and efflorescences. Its most characteristic feature is its intense, canary-yellow or greenish-yellow color. ## Physical Properties Delrioite crystals exhibit a silky or dull luster, depending on their form of occurrence. The mineral is very soft, with a Mohs hardness of approximately 2. It is translucent. Due to the small size of the crystals, precise determination of density is difficult, but the calculated value is approximately 2.8 g/cm³. ## Colors and Varieties Delrioite occurs in uniform shades, from canary-yellow to greenish-yellow. No color or commercial varieties are distinguished. ## History and Name The mineral was discovered in 1959 in a uranium-vanadium mine in Montrose County, Colorado, USA. Its name honors Andrés Manuel del Río (1764-1849), a Spanish-Mexican mineralogist who first discovered the element vanadium, initially naming it "erythronium." ## Uses Delrioite has no industrial applications. It is valued solely as a collector's mineral due to its rarity and intense color.

Properties

Mohs hardness
2
Luster
Silky
Streak
Yellow
Density
2.8
Cleavage
Perfect on {010}
Fracture
Uneven
Transparency
Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Delrioite can be identified by its characteristic canary-yellow color, fibrous or platy crystal habit, and occurrence in association with other vanadium minerals on sandstones. It is very soft and often forms coatings. ## Distinguishing from Similar Minerals Delrioite is sometimes confused with other secondary vanadium minerals, such as tyuyamunite or carnotite. It is distinguished from them by its lack of radioactivity (carnotite and tyuyamunite contain uranium) and specific mineral parageneses. Accurate identification requires advanced analytical methods, e.g., XRD. ## Crystal Forms Crystals are very small, usually platy or acicular in habit, elongated along one axis. They often form radial or tangled aggregates, as well as thin coatings and efflorescences on the host rock.

Geological environment

## Genesis Delrioite is a secondary mineral formed in the oxidation zones of uranium-vanadium deposits, which occur in sedimentary rocks, mainly sandstones. It forms as a result of the weathering of primary vanadium minerals under conditions of low temperature and pressure. ## Mineral Associations This mineral often co-occurs with other vanadates, such as metarossite, pascoite, rossite, as well as montmorillonite, gypsum, and other secondary minerals. ## Localities The most important and best-documented locality for delrioite is its type locality - the Jo Dandy mine in Paradox Valley, Montrose County, Colorado, USA. This is the only place where this mineral has been found in larger quantities.

Rarity

Very rare

For collectors

## Quality Criteria Most valued by collectors are specimens with rich, dense aggregates of intensely colored, canary-yellow crystals that contrast sharply with the host rock (matrix). Due to the microscopic size of the crystals, specimens are primarily judged on the aesthetics of the entire aggregate and its abundance. ## Popular Localities The only source of collector specimens is the historic type locality in Colorado, USA. All specimens available on the market originate from this single location.

Care and storage

## Cleaning Delrioite specimens are extremely delicate and fragile. They should only be cleaned using compressed air to remove dust. Any contact with water or chemicals is inadvisable. ## What to Avoid Avoid contact with water, as the mineral is partially soluble in it. Protect it from all chemicals, ultrasound, and high temperatures. Due to its low hardness, any friction and contact with harder minerals should be avoided. ## Storage It is recommended to store specimens in closed, padded collector boxes (so-called "micromount boxes") to protect them from mechanical damage, dust, and moisture. Avoid exposure to direct sunlight.

Sources

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