Kintoreite

Chemical formula: Pb₂+Fe₃+₃(PO₄)(PO₃OH)(OH)₆

Kintoreite is a rare secondary mineral from the jarosite group, a phosphate analogue of beudantite, valued by collectors for its microcrystalline aggregates.

## Characteristics Kintoreite is a hydrated lead iron phosphate belonging to the alunite supergroup. It forms very small, rhombohedral or pseudocubic crystals, rarely exceeding 0.5 mm. It most often occurs as microcrystalline druses, coatings, and earthy aggregates, densely covering the surface of host rocks. ## Physical Properties Kintoreite crystals exhibit a vitreous to resinous luster. The mineral is brittle and has a hardness of about 4.5 on the Mohs scale. Its density is relatively high, approximately 4.33 g/cm³, which is typical for lead-bearing minerals. ## Colors and Varieties Kintoreite occurs in various shades of yellow, green, and brown. Colors range from pale yellow, through yellowish-green, olive-green, to reddish-brown. Some specimens can be almost colorless. No named varieties are distinguished. ## History and Name The mineral was discovered in the Kintore mine in the Broken Hill region of New South Wales (Australia). It was described in 1995 by E. H. Nickel, B. W. Robinson, O. FitzGerald, W. D. Birch, J. L. Bodkin, and W. G. Mumme. The name comes from its type locality (the place of its first finding). ## Uses Kintoreite has no industrial applications. It is solely a mineral of scientific and collector's interest, sought after for its rarity and attractive microcrystals.

Properties

Mohs hardness: 4.5
Luster: Vitreous to Resinous
Streak: Pale yellow
Density: 4.33
Cleavage: None
Fracture: Conchoidal
Transparency: Translucent to Opaque
Crystal system: Trigonal

Diagnostic features

## Identification Kintoreite is difficult to identify without specialized equipment. Preliminary identification is possible due to its characteristic color (yellow, green, brown), high density, and co-occurrence with other secondary lead minerals and phosphates in the oxidation zones of ore deposits. ## Distinguishing from Similar Minerals It can be confused with other minerals from the alunite supergroup, such as beudantite, segnitite, corkite, or hinsdalite, which form similar crystals and occur in the same environments. Definitive differentiation requires chemical analysis (EDS/XRD) to confirm the dominance of phosphorus over arsenic and sulfur. ## Crystal Forms Crystals are usually very small, rhombohedral in habit, often appearing cubic (pseudocubic). They form druses, crusts, and earthy aggregates.

Geological environment

## Genesis Kintoreite is a secondary mineral, forming in the oxidation zones (gossans) of polymetallic hydrothermal deposits rich in lead, iron, and phosphorus. It forms as a result of the weathering of primary sulfides (mainly galena and pyrite) in the presence of phosphate minerals, such as apatite. ## Mineral Associations It often co-occurs with other secondary minerals such as pyromorphite, beudantite, segnitite, corkite, hinsdalite, libethenite, dufrenite, goethite, hematite, and quartz. ## Localities Key localities worldwide include the type locality in Kintore and Block 14, Broken Hill, New South Wales (Australia); the Clara mine in the Black Forest (Germany); the Tsumeb mine (Namibia); as well as some deposits in Cornwall (United Kingdom) and Nevada (USA).

Rarity

Rare

For collectors

## Quality Criteria Specimens with well-formed, sharp, and lustrous microcrystals of intense, pure color (e.g., vivid green or canary yellow) are most valued by collectors. Contrast with the rock matrix, as well as the richness and aesthetics of the entire druse, are also important. Specimens with visible, individual crystals are rated much higher than earthy aggregates. ## Popular Localities Specimens from the Clara mine in Germany and Broken Hill in Australia are considered classic and most sought after by collectors specializing in rare minerals and micromounts.

Care and storage

## Cleaning Specimens should be cleaned very carefully, using a soft brush to remove dust. Compressed air can be used (from a safe distance). Due to the presence of lead, avoid inhaling dust and wash hands after contact with the mineral. ## What to Avoid Avoid contact with acids and strong chemicals, which can damage or dissolve the mineral. Do not heat it or expose it to sudden temperature changes. Due to its brittleness, protect it from impacts and vibrations. ## Storage Kintoreite specimens are best stored in closed, padded "micromount" boxes to protect delicate crystals from mechanical damage and dust. Display should be away from direct sunlight and heat sources.

Sources

IMA Mineral List (CNMNC)