Mikehowardite
Chemical formula: Fe<sup>3+</sup><sub>4</sub>(V<sup>5+</sup>O<sub>4</sub>)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>·H<sub>2</sub>O
Mikehowardite is a very rare, hydrated iron vanadate, forming characteristic, tabular crystals of a reddish-brown color.
Description
## Characteristics Mikehowardite is a mineral from the vanadate group, chemically classified as a hydrated iron(III) vanadate. It forms very small, thin, tabular crystals, flattened in one plane. These crystals often combine into rosette-like or radiating aggregates, which are its most typical form of occurrence. It has an intense, reddish-brown to orange-brown color and exhibits a luster similar to diamond (subadamantine). ## Physical Properties This mineral is relatively soft, with a hardness of about 3 on the Mohs scale. It is brittle and has excellent cleavage in one plane, which accounts for its tabular appearance. Its density is calculated to be 3.45 g/cm³. It is translucent. ## Colors and Varieties It occurs in shades from reddish-brown to orange-brown. No color or commercial varieties have been distinguished. ## History and Name The mineral's name honors Michael “Mike” Howard (born 1946), a renowned American mineral collector and owner of the Howard Mineral Collection. It was officially approved by the International Mineralogical Association (IMA) in 2013. It was described by a team of mineralogists led by Anthony R. Kampf. ## Applications Due to its extreme rarity, mikehowardite has no industrial applications. It is solely an object of interest for collectors specializing in rare minerals and micromounts.
Diagnostic features
## Identification Characteristic features include its reddish-brown color, subadamantine luster, and the form of thin, tabular crystals forming rosette-like aggregates. Its environment of occurrence – the oxidation zone of uranium-vanadium deposits – is also of key importance. ## Distinguishing from Similar Minerals It can be confused with other rare, secondary vanadates. It is distinguished from hewettite by its tabular, rather than fibrous, crystal form. It differs from pascoite typically by its darker, more brownish color and aggregate form. Certain identification requires advanced analytical methods, such as chemical composition analysis (EDS) or X-ray diffraction (XRD). ## Crystal Forms It forms thin, tabular crystals, often flattened. These crystals aggregate into characteristic, rosette-like or fan-shaped clusters.
Geological environment
## Genesis It is a secondary mineral, forming in the oxidation zones of uranium-vanadium deposits in sandstones. It forms at low temperatures as a result of the alteration of earlier vanadium minerals, such as montroseite. ## Mineral Associations It co-occurs with other rare vanadium minerals, such as howardevansite, hughesite, montroseite, and sherwoodite. ## Localities The only confirmed locality in the world is the West Sunday mine in the Slick Rock district, San Miguel County, Colorado (USA). This is its type locality.
Rarity
Very rare
Collector aspects
## Quality Criteria The most highly valued specimens are those with well-formed, sharp crystals forming aesthetic rosettes. The intensity and saturation of the color are important, as is the size of the aggregates and their contrast with the rock matrix. Specimens with accompanying other rare vanadates are particularly sought after. ## Popular Localities All known collector specimens come from a single location – the West Sunday mine in Colorado, USA.
Care and storage
## Cleaning Specimens should only be dry cleaned, using a soft brush or compressed air from a safe distance. Avoid contact with water and any chemical agents. ## What to Avoid The mineral is soft, brittle, and susceptible to scratches. As a hydrated mineral, it can be unstable under high temperature or very low humidity conditions, which can lead to its dehydration and structural damage. Avoid ultrasonic cleaners, acids, and detergents. ## Storage It is recommended to store specimens in separate, padded “micromount” boxes, away from harder minerals. Stable temperature and humidity conditions should be ensured, protecting them from direct sunlight and dust.