Protasite

Chemical formula: Ba(U₆+O₂)₃O₃(OH)₂·₃H₂O

Protasyte is a rare, highly radioactive secondary uranium mineral, forming aggregates of small, golden-yellow crystals.

## Characteristics Protasyte is a mineral from the uranyl oxide group, characterized by an intense, golden-yellow or orange-yellow color. It most often occurs as very small, platy or acicular crystals, which form radial aggregates, rosettes, as well as earthy coatings and crusts. Due to the small size of the crystals, specimens usually appear as microminerals. ## Physical properties Protasyte crystals exhibit a vitreous luster, transitioning to silky in the case of fine-fibrous aggregates. It is a translucent to opaque mineral. It has a very high density, approximately 5.93 g/cm³, which is typical for uranium minerals. Hardness has not been precisely determined due to the small size and brittleness of the crystals. ## Colors and varieties This mineral does not form color varieties or commercial varieties. Its color is constant and ranges within a narrow spectrum from golden-yellow to orange-yellow. ## History and name Protasyte was first described in 1983 by Michel Deliens and Paul Piret. Its name honors Jean Protas (1932–2007), a French crystallographer and mineralogist from the University of Nancy, for his contributions to the study of uranium minerals. The type locality (locus typicus) is the Shinkolobwe mine in Katanga Province, Democratic Republic of Congo. ## Applications Due to its rarity and strong radioactivity, protasyte has no industrial application. It is solely an object of scientific interest and a valued collector's mineral.

Properties

Luster: Vitreous to silky
Streak: Light yellow
Density: 5.93
Cleavage: Perfect on {010}
Transparency: Translucent to opaque
Crystal system: Monoclinic

Diagnostic features

## Identification The key diagnostic feature of protasyte is its very strong radioactivity, which can be easily detected with a Geiger counter. Other helpful identification features include its intense yellow color, high density, and characteristic form of small, platy or acicular crystals forming aggregates. Co-occurrence with other secondary uranium minerals is also an important clue. ## Distinguishing from similar minerals Protasyte is visually almost identical to many other yellow secondary uranium minerals, such as becquerelite, masuyite, fourmarierite, or uranophane. Reliable differentiation of these minerals based on physical characteristics is impossible. Definitive identification requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical microanalysis (EDS/WDS), which can detect barium – an element characteristic of protasyte. ## Crystal forms It forms elongated, flattened crystals with a platy or acicular habit. These crystals rarely occur individually, most often coalescing into radial or stellate aggregates, rosettes, and also forming coatings and crusts.

Geological environment

## Genesis Protasyte is a secondary mineral, formed in the oxidation (weathering) zones of uranium deposits. It forms as a result of hydrothermal alteration of primary uranium minerals, mainly uraninite, in the presence of barium-rich solutions. ## Mineral associations It most often co-occurs with other secondary uranium minerals, such as uranophane, becquerelite, curite, fourmarierite, kasolite, and soddyite. Primary uraninite is also associated with it. ## Localities The most important and classic locality for protasyte is the Shinkolobwe mine in the Democratic Republic of Congo, from which the best specimens originate. It is also known from several other localities worldwide, including the Krunkelbach Valley in the Black Forest (Germany).

Rarity

Very rare

For collectors

## Quality criteria The quality of protasyte specimens is primarily assessed based on the intensity and purity of the color and the crystal habit, even if they are microscopic in size. Well-defined, radial aggregates on a contrasting matrix are particularly valued. Association with other rare uranium minerals is also important. Due to the nature of the mineral, clarity (transparency) and the size of individual crystals are secondary factors. ## Popular localities Specimens from the type locality – the Shinkolobwe mine in the Democratic Republic of Congo – are by far the most valued and sought after by collectors. This locality is historically most important for uranium mineralogy and has provided the best known protasyte specimens.

Care and storage

## Cleaning Protasyte is a very brittle and delicate mineral. Cleaning specimens is not recommended. If absolutely necessary, a soft brush can be used to dry-remove dust. Avoid contact with water and any chemical agents. ## What to avoid The mineral is highly radioactive. Direct skin contact, inhalation of dust, and storage in areas of constant human presence must be strictly avoided. It should not be heated or exposed to acids. It is brittle and sensitive to shocks and abrasion. ## Storage Protasyte specimens must be stored with extreme caution. They should be placed in a tightly sealed, lead or lead-lined container, which will act as a barrier to radiation. The container must be clearly marked with the international radioactivity symbol and the full name of the mineral. Store away from bedrooms, living rooms, and workplaces.

Sources

IMA Mineral List (CNMNC)