Bamfordite
Chemical formula: Fe<sup>3+</sup>Mo<sup>6+</sup><sub>2</sub>O<sub>6</sub>(OH)<sub>3</sub>·H<sub>2</sub>O
Bamfordite is a very rare hydrated iron molybdate, forming microscopic, acicular crystals of an intense orange color.
Properties
- Mohs hardness
- 2
- Luster
- Silky
- Streak
- Pale orange
- Density
- 3.85
- Cleavage
- Perfect on {010}
- Fracture
- Splintery
- Transparency
- Translucent
- Crystal system
- Triclinic
Diagnostic features
## Identification Bamfordite can be identified by its characteristic form – radial aggregates composed of very fine, acicular crystals. Key features include its intense orange color and silky luster. It occurs in a specific environment – as an oxidation product of molybdenite. ## Distinguishing from similar minerals It can be confused with other secondary molybdates, such as wulfenite or ferrimolybdite. It is distinguished from wulfenite by its acicular crystal habit (wulfenite forms tabular or pyramidal crystals). Ferrimolybdite, also acicular, typically has a more yellow or canary-yellow color and is often difficult to distinguish without advanced analyses (e.g., XRD). ## Crystal forms Crystals are strongly elongated, acicular, or bladed. They form characteristic radial or stellate aggregates, as well as fibrous crusts and coatings.
Geological environment
## Genesis Bamfordite is a secondary mineral, forming in the oxidation (weathering) zone of ore deposits containing molybdenite (MoS₂). It forms as a result of the action of iron-rich solutions on primary molybdenum sulfides. It originates under low temperature and pressure conditions, directly on the surface of host rocks. ## Mineral associations It most commonly co-occurs with the mineral from which it forms – molybdenite. It is also accompanied by other minerals of the oxidation zone, such as quartz, muscovite, pyrite, goethite, jarosite, and the rare ferrimolybdite. ## Localities This is an extremely rare mineral, known from only a few localities worldwide. The most important and type locality is Bamford Edge in Derbyshire, England. Additionally, it has been confirmed in small quantities at the Leona mine in Arizona (USA) and in several locations in Japan (Hirase and Tsumo mines in Gifu Prefecture).
Rarity
Very rare
For collectors
## Quality criteria The most prized bamfordite specimens are those with well-formed, rich radial aggregates of intense orange color. Contrast with the rock matrix (preferably light quartz) and absence of damage to the delicate needles are important. Due to the microscopic nature of the mineral, specimens are evaluated under magnification. The size of the entire specimen is less important than the quality and abundance of the bamfordite crystals themselves. ## Popular localities By far the most sought-after and classic specimens come from the type locality – Bamford Edge in England. Material from this location is considered exemplary for the species.
Care and storage
## Cleaning Bamfordite specimens are extremely delicate and susceptible to mechanical damage. Cleaning should be kept to an absolute minimum. If necessary, compressed air (from a safe distance) can be used to remove dust. Any contact with water, brushes, or other tools should be avoided. ## What to avoid Water, chemicals, ultrasonics, and sudden temperature changes must be strictly avoided. Even gentle touching can destroy the microscopic crystals. The mineral should be protected from direct sunlight, which can cause fading, and from humidity. ## Storage It is recommended to store specimens exclusively in closed, padded "micromount" boxes, which protect against dust, shocks, and humidity changes. Display should only take place under stable conditions, away from sources of vibration.