Upalite

Chemical formula: Al(U⁶⁺O₂)₃(PO₄)₂O(OH)·₇H₂O

Upalite is a rare, radioactive secondary mineral of the uranyl phosphate group, forming characteristic, acicular crystals of an amber-yellow color.

## Characteristics Upalite is a hydrated uranyl and aluminum phosphate, belonging to the phosphuranylite group. This mineral forms very fine, acicular or hair-like crystals, which often occur as radial aggregates, crusts, or spherulites. Individual crystals are usually too small to be seen with the naked eye, and their clusters appear as felt-like or silky masses. ## Physical Properties Upalite crystals are transparent to translucent and exhibit a vitreous luster. The mineral's hardness on the Mohs scale is approximately 3, and its density is 3.9 g/cm³. It is a brittle mineral, and its crystals are flexible. ## Colors and Varieties Upalite occurs in characteristic shades of yellow, from amber-yellow to yellowish-brown. No color or commercial varieties are distinguished. ## History and Name The name "upalite" is an acronym derived from the mineral's chemical composition: **U**ranium, **P**hosphate, and **Al**uminum. It was first described in 1978 by Michel Deliens and Paul Piret based on samples from the Kobokobo pegmatite in the Democratic Republic of Congo, which is its type locality. ## Uses Due to its rarity, small crystal size, and radioactivity, upalite has no industrial application. It is of scientific interest only and is sought after by specialized collectors of uranium minerals.

Properties

Mohs hardness: 3
Luster: Vitreous
Streak: White
Density: 3.9
Cleavage: {010}, distinct
Fracture: Uneven
Transparency: Transparent,Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification Upalite can be identified by its characteristic amber-yellow color, acicular crystal form, and occurrence as radial or felt-like aggregates. A key diagnostic feature is its strong radioactivity, easily detectable with a Geiger counter. Under shortwave ultraviolet light, it exhibits weak, green fluorescence. ## Distinguishing from Similar Minerals Upalite can be confused with other secondary uranium minerals of similar color and form, such as meta-autunite, phosphuranylite, or meta-torbernite. Distinguishing it from these minerals based on visual characteristics is extremely difficult and usually requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS). ## Crystal Forms Upalite crystals are prismatic and very elongated, with an acicular or hair-like appearance. They usually form radial aggregates, rosettes, spherulites, or dense, felt-like crusts on the surface of the host rock.

Geological environment

## Genesis Upalite is a secondary mineral, meaning it forms as a result of the weathering and alteration of primary uranium minerals, such as uraninite. It forms in the oxidation zones of uranium deposits, especially in granitic pegmatites rich in phosphates. ## Mineral Associations This mineral often co-occurs with other secondary uranium minerals, such as autunite, meta-autunite, torbernite, phosphuranylite, as well as with host rock minerals like quartz, feldspars, and micas. ## Localities The most important and well-documented occurrence of upalite is its type locality – the Kobokobo pegmatite in South Kivu Province, Democratic Republic of Congo. This is the only place from which well-formed, rich specimens of this mineral originate.

Rarity

Very rare

For collectors

## Quality Criteria The most valuable upalite specimens are characterized by an intense, amber-yellow color and distinctly formed, radial aggregates of acicular crystals. Specimens in which the delicate upalite structures are well-preserved and contrast with the darker host rock are highly prized. Due to the microscopic size of individual crystals, the aesthetics and richness of the entire aggregate are primarily evaluated. ## Popular Localities The only source of collectible specimens of market significance is the Kobokobo pegmatite in the Democratic Republic of Congo. Specimens from this locality are the standard for this species.

Care and storage

## Cleaning Upalite is a very brittle and sensitive mineral. Mechanical cleaning is not recommended. If absolutely necessary, a stream of compressed air can be used to remove loose dust particles. Avoid contact with water and any chemicals. ## What to Avoid As a uranium mineral, upalite is highly radioactive. Inhaling dust and direct skin contact must be strictly avoided. It should not be stored in areas where a lot of time is spent. It is sensitive to changes in temperature and humidity. It should be protected from direct sunlight, which can cause dehydration and color change. ## Storage Upalite specimens must be stored in specialized, sealed containers with appropriate radioactive warning labels. It is best to keep them in lead-lined or thick-walled plastic boxes, away from other minerals that could suffer radiation damage. Store in a dry and cool place, away from people.