Waylandite
Chemical formula: Bi<sup>3+</sup>Al<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub>(OH)<sub>6</sub>
Waylandite is a rare bismuth aluminum phosphate, forming microscopic, white or cream-colored aggregates and crusts.
Properties
- Mohs hardness
- 4.5
- Luster
- Vitreous
- Streak
- White
- Density
- 3.85
- Cleavage
- Perfect on {0001}
- Fracture
- Uneven
- Transparency
- Translucent to opaque
- Crystal system
- Trigonal
Diagnostic features
## Identification Identifying waylandite without advanced analytical methods (such as XRD or EDS) is practically impossible. Preliminary field identification relies on observing the geological environment – its occurrence in the oxidation zones of bismuth-rich ore deposits, in association with other rare phosphates. Its white, earthy, or very fine-grained aggregates are an indication, but not a definitive characteristic. ## Distinguishing from Similar Minerals Macroscopically, waylandite is indistinguishable from many other white and cream-colored secondary minerals, such as crandallite, wardite, wavellite, or minerals from the alunite group. Definitive differentiation requires chemical analysis confirming the presence of bismuth, aluminum, and phosphorus. ## Crystal Forms Waylandite crystallizes in the trigonal system. It forms very small, tabular or rhombohedral crystals, usually less than 0.1 mm in size. It is most commonly found in the form of spherulitic or radial aggregates, as well as massive, cryptocrystalline crusts.
Geological environment
## Genesis Waylandite is a secondary phosphate mineral that forms in the oxidation (weathering) zones of hydrothermal deposits, especially those rich in bismuth. It forms as a result of the reaction of phosphate-bearing solutions with primary bismuth and aluminum minerals in granitic pegmatites or quartz veins. ## Mineral Associations This mineral often co-occurs with other phosphates, arsenates, and bismuth minerals. Typical associated minerals include bismutite, scorodite, crandallite, wardite, wavellite, quartz, muscovite, beryl, and various iron oxides. ## Localities The most important and classic locality, from which the type material originates, is the Beryl-Tantalite mine in Wampewo, Uganda. Other confirmed localities include the Silver Coin mine in Valmy, Nevada (USA), the Clara mine in the Black Forest (Germany), as well as occurrences in Cornwall (United Kingdom) and Sardinia (Italy).
Rarity
Very rare
For collectors
## Quality Criteria The quality of a waylandite specimen is primarily assessed based on the richness and visibility of the aggregates on the rock matrix. Since the crystals are microscopic, specimens with clearly formed spherulites or dense crusts are more highly valued. Color contrast with the substrate (e.g., white waylandite on dark rock) also enhances visual appeal. Association with other rare minerals is a significant advantage. ## Popular Localities Specimens from the type locality in Uganda are historically most important but extremely difficult to acquire. Specimens from the Clara mine in Germany, known for supplying well-formed microcrystals of many rare minerals, are most commonly found on the collector's market.
Care and storage
## Cleaning Waylandite specimens are usually very delicate and consist of microscopic crystals. Cleaning should be kept to an absolute minimum. If necessary, compressed air can be used to remove dust. Avoid contact with water, which can damage delicate aggregates or the host rock. ## What to Avoid Ultrasonic cleaners, all chemicals, acids, and detergents must be absolutely avoided. The mineral is sensitive to chemical action. It should also be protected from high temperatures and mechanical shocks. ## Storage Waylandite specimens are best stored in sealed "micromount" boxes, which protect them from dust, moisture, and mechanical damage. Due to the small size of the crystals, this mineral is not intended for display outside of specialized packaging.