Raspite
Chemical formula: Pb<sup>2+</sup>W<sup>6+</sup>O<sub>4</sub>
Raspite is a rare polymorphic lead tungstate mineral, prized by collectors for its characteristic, flattened crystals with sharp terminations and unique form.
Properties
- Mohs hardness
- 2.5-3
- Luster
- Adamantine, Resinous
- Streak
- Yellowish white
- Density
- 8.46
- Cleavage
- Good on {100}
- Fracture
- Uneven
- Transparency
- Transparent to Translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification The key diagnostic feature of raspite is its unique crystal habit: thin, flattened tablets or blades, often with a wedge-shaped, sharp termination. High density, adamantine luster, and characteristic yellowish-brown color are also important indicators. Occurrence in association with other lead minerals, especially stolzite, in the oxidation zones of ore deposits, is a strong diagnostic signal. ## Distinguishing from Similar Minerals Raspite is most often confused with its polymorph, stolzite. However, stolzite crystallizes in the tetragonal system, forming bipyramidal or thick-tabular crystals, in contrast to the monoclinic, bladed crystals of raspite. It is distinguished from wulfenite by its crystal habit (wulfenite forms thin, square tablets) and chemical composition (wulfenite is a lead molybdate). Despite similar colors, crystal habit is usually sufficient to differentiate them. ## Crystal Forms Raspite crystallizes in the monoclinic system. Typical forms are thin, flattened tabular crystals, elongated along one axis, giving them the appearance of blades or lamellae. They often exhibit sharp, wedge-shaped terminations. Crystals rarely form larger aggregates, most often occurring as single, overgrown individuals.
Geological environment
## Genesis Raspite is a secondary mineral, forming in the oxidation zones (so-called iron caps) of lead ore deposits where tungsten-bearing minerals were also present. It crystallizes under low-temperature conditions, often in association with its polymorph, stolzite. Its formation is linked to the weathering of primary lead sulfides (such as galena) and tungstates. ## Mineral Associations This mineral often co-occurs with its polymorph, stolzite. Other associated minerals include cerussite, anglesite, pyromorphite, as well as various iron and manganese oxides (e.g., goethite, hematite), which form the host rock. ## Localities The type locality and simultaneously the source of the world's best specimens is the Broken Hill mine in New South Wales, Australia. Most collectible raspites originate from there. Other confirmed, though much less significant, localities include the Cordillera mine in Lander County (Nevada, USA) and several places in Mexico (e.g., Erupción-Fortuna mine in Chihuahua).
Rarity
Very rare
For collectors
## Quality Criteria The most highly prized raspite specimens are characterized by sharply terminated, well-formed crystals with an intense, yellowish-brown color and strong luster. Form is key – the more "book-like," bladed, and sharp the crystal, the better. The aesthetics of the composition are also important – a single, large (for this mineral, meaning over 5 mm) crystal on a contrasting matrix of iron oxides is much more valuable than a tangled aggregate. Clarity and transparency also increase the specimen's value. ## Market Prices Raspite is an expensive collectible mineral. Prices for micromounts (single, small crystals under 2-3 mm) start from tens to over a hundred dollars. Better quality miniatures with well-formed crystals several millimeters in size, especially on matrix, can cost from several hundred to several thousand dollars, depending on the quality and aesthetics of the specimen. ## Popular Localities The absolutely dominant and most sought-after locality is the Broken Hill mine in Australia. Specimens from this location are considered the global standard for raspite and fetch the highest prices on the collector's market.
Care and storage
## Cleaning Raspite specimens should be cleaned with the utmost care due to their fragility and softness. The safest method is to use compressed air to remove dust. If wet cleaning is necessary, use only distilled water and a very soft brush, avoiding any pressure on the crystals. After cleaning, the specimen should be left to air dry completely at room temperature. ## What to Avoid Raspite is sensitive to chemicals, especially acids and bases, which can damage it. Ultrasonic cleaners, which could destroy delicate crystals, should be avoided. The mineral is also sensitive to sudden temperature changes and mechanical damage (scratches, impacts). ## Storage Raspite specimens are best stored in individual, padded "micromount" boxes to protect them from dust, light, and mechanical damage. It should not be stored with harder minerals that could scratch it. Due to its lead content, it is recommended to wash hands after contact with the mineral.