Rowleyite

Chemical formula: [Na(N₃-H₄,K)₉Cl₄][(V₅+,V₄+)₂(P,As₅+)O₈]₆·n[H₂O,Na,N₃-H₄,K,Cl]

Rowleyite is an extremely rare, hydrated vanadate-phosphate chloride of sodium and potassium, forming microscopic, cubic crystals.

## Characteristics Rowleyite is a mineral with a complex chemical composition, belonging to the vanadate group. It occurs as extremely small, individual crystals with a perfectly cubic shape, reaching a size of up to about 40 micrometers. The crystals are transparent and characterized by an intense, reddish-orange color. Due to the extremely small size of the crystals, observation of visual features requires the use of an electron microscope. ## Physical properties Because of the microscopic size of the crystals, most physical properties, such as hardness, luster, or density, have not been precisely measured. The luster is described as vitreous. The mineral is brittle. ## Colors and varieties This mineral occurs in a uniform, reddish-orange color. No varieties are known. ## History and name Rowleyite was discovered in the Rowley mine in Maricopa County, Arizona, USA. Its name comes from its type locality. It was approved as a new mineral by the International Mineralogical Association (IMA) in 2016 under number IMA2016-053. It was described by Anthony R. Kampf and collaborators in 2017. ## Applications Rowleyite has no industrial application. It is of purely scientific and collector interest due to its extreme rarity and unique chemical composition.

Properties

Luster: Vitreous
Streak: Orange
Cleavage: None
Fracture: Conchoidal
Transparency: Transparent
Crystal system: Cubic

Diagnostic features

## Identification Identification of rowleyite is impossible without advanced analytical techniques. Its characteristic cubic crystal shape, reddish-orange color, and occurrence in a specific geological environment are distinctive. Final confirmation requires chemical analysis (EDS) and crystallographic studies (XRD). ## Distinguishing from similar minerals Based on appearance alone, it is practically impossible to distinguish from other microscopic, red or orange secondary minerals, such as mimetite or vanadinite, which may co-occur in the same environment. Key factors are checking for the perfectly cubic crystal form and confirming the chemical composition. ## Crystal forms Rowleyite forms exclusively single, sharply defined, perfect cubes not exceeding 40 micrometers in size.

Geological environment

## Genesis Rowleyite is a secondary mineral that formed as a result of hydrothermal processes occurring in the oxidation zone of polymetallic deposits. It crystallizes in cavities within volcanic rocks (basalt), in an environment rich in vanadium, phosphorus, chlorine, and sodium and potassium. ## Mineral associations This mineral co-occurs with other secondary vanadate and phosphate minerals. At the type locality, it was found in association with wulfenite, vanadinite, mimetite, quartz, calcite, fluorite, and barite. ## Localities The only confirmed locality for rowleyite in the world is the Rowley mine, located in the Painted Rock Mountains mining district in Maricopa County, Arizona, USA.

Rarity

Extremely rare

For collectors

## Quality criteria The quality of a rowleyite specimen depends on the number, sharpness, and size of the microscopic crystals on the rock matrix. The most desirable specimens are those with clearly visible, undamaged cubes, preferably in rich clusters or in association with other rare minerals. Color contrast with the matrix also enhances aesthetic value. ## Popular localities The only source of specimens is the Rowley mine in Arizona, USA. This locality is known for the occurrence of many rare and well-formed secondary minerals, making it popular among collectors specializing in "micromounts."

Care and storage

## Cleaning Rowleyite specimens are extremely small and delicate, found on a rock matrix. They should not be cleaned mechanically or chemically. Any attempts at cleaning may irreversibly destroy the microscopic crystals. ## What to avoid Avoid contact with any liquid, chemicals, and also ultrasound. Specimens should be protected from dust, vibrations, and sudden temperature changes. The mineral is water-soluble. ## Storage Specimens should be stored only in specialized, sealed "micromount" boxes, protecting them from dust and mechanical damage. Store in stable room conditions, away from heat sources and humidity.

Sources

IMA Mineral List (CNMNC)