Kasolite

Chemical formula: Pb<sup>2+</sup>(U<sup>6+</sup>O<sub>2</sub>)SiO<sub>4</sub>·H<sub>2</sub>O

Kasolite is a rare, highly radioactive uranyl lead silicate, forming small, acicular crystals of an intense yellow or orange color.

## Characteristics Kasolite is a hydrated uranyl lead silicate, belonging to the uranyl silicate group. This mineral most often forms very small, acicular or prismatic crystals, which rarely exceed a few millimeters in length. It occurs as radial aggregates, fibrous masses, and also as coatings and crusts on other uranium minerals. Its appearance is very distinctive due to its intense, bright colors. ## Physical Properties Kasolite crystals exhibit a hardness in the range of 4-5 on the Mohs scale. They are brittle and have a relatively high density, ranging from 5.9 to 6.5 g/cm³, which is typical for minerals containing lead and uranium. The luster is variable, from vitreous on crystal faces to dull or earthy in the case of fine-grained aggregates. It is a highly radioactive mineral. ## Colors and Varieties Kasolite ranges in color from intense yellow, through orange-yellow, orange, to brownish and greenish-yellow. The color is directly related to the presence of the uranyl group (UO₂)2+. No named commercial or color varieties are distinguished. ## History and Name The mineral was first described in 1921 by Alfred Schoep. Its name comes from the discovery locality – the Shinkolobwe mine (formerly known as Kasolo) in Katanga Province, Democratic Republic of Congo. This location is the type locality for this mineral. ## Uses Due to its rarity and small crystal size, kasolite has no industrial application. It is solely an object of interest for collectors specializing in uranium minerals and has scientific significance.

Properties

Mohs hardness
4-5
Luster
Vitreous, Resinous, Dull
Streak
Yellow-brown
Density
5.9-6.5
Cleavage
Good on {001}
Fracture
Uneven
Transparency
Transparent to Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Key diagnostic features of kasolite are its intense yellow to orange color, characteristic crystal forms (small needles and prisms), and high density. The most important feature, however, is its strong radioactivity, easily detectable with a Geiger-Müller counter. It occurs in the oxidation zones of uranium deposits. ## Distinguishing from Similar Minerals Kasolite can be confused with other secondary uranium minerals of similar color, such as uranophane, boltwoodite, or sklodowskite. Uranophane often forms similar radial aggregates but has a lower density and is usually more greenish-yellow. Boltwoodite is also lighter. Precise differentiation of these minerals in many cases requires advanced chemical (EDS) or X-ray (XRD) analyses. ## Crystal Forms Kasolite crystallizes as elongated, flattened prismatic crystals, often with a bladed cross-section. These crystals typically form radial or stellate aggregates, as well as fan-shaped masses. It also occurs as earthy masses, powdery coatings, and crusts.

Geological environment

## Genesis Kasolite is a typical secondary mineral, forming in the oxidation (weathering) zone of hydrothermal uranium deposits. It forms as a result of reactions of silica-rich waters with primary uranium minerals, such as uraninite, in the presence of lead originating from the radioactive decay of uranium or from other minerals (e.g., galena). ## Mineral Associations This mineral often co-occurs with other secondary uranium minerals. Its most common associations include: uranophane, sklodowskite, torbernite, autunite, curite, as well as primary uraninite. It can also be accompanied by minerals such as quartz, hematite, or clay minerals. ## Localities The most important and classic locality for kasolite is the Shinkolobwe mine in the Democratic Republic of Congo, from which the best specimens originate. Significant deposits are also found in Jáchymov in the Czech Republic, Wölsendorf in Bavaria (Germany), and the Great Bear Lake region in Canada. It also occurs in many uranium deposits in the USA, especially in Utah and Arizona.

Rarity

Rare

For collectors

## Quality Criteria Specimens with well-formed, sharp crystals of intense, orange color are most valued by collectors. Rich aggregates of radial masses on a contrasting matrix are highly prized. Crystal size is crucial – specimens with needles exceeding a few millimeters are rare. Aesthetic composition and lack of damage are also important. ## Popular Localities Specimens from the Shinkolobwe mine in the Democratic Republic of Congo are considered the best in the world and serve as a benchmark for this mineral. High-quality microcrystals also come from German localities, such as Wölsendorf. Czech Jáchymov has provided many historical specimens of scientific importance.

Care and storage

## Cleaning Kasolite is a brittle and sensitive mineral. Cleaning should be limited to an absolute minimum. If necessary, a very soft brush can be used to dry-remove dust. Avoid contact with water, which can damage delicate crystals. ## What to Avoid The mineral is highly radioactive – it is absolutely essential to avoid inhaling dust and direct skin contact. Washing hands after every contact is mandatory. It should not be heated or exposed to any chemicals. Store away from sunlight, which can cause fading. ## Storage Kasolite specimens must be stored in specialized, sealed plastic containers (e.g., perky box), clearly marked as radioactive material. These containers should be kept in a location isolated from permanent human presence, preferably in a lead container, which limits radiation emission.

External references

Sources

Read more