Puttapaite
Chemical formula: Pb<sup>2+</sup><sub>2</sub>Mn<sup>2+</sup><sub>2</sub>Zn<sup>2+</sup>Cr<sup>3+</sup><sub>4</sub>O<sub>2</sub>(As<sup>5+</sup>O<sub>4</sub>)<sub>4</sub>(OH)<sub>6</sub>(H<sub>2</sub>O)<sub>12</sub>
Puttapaite is an extremely rare zinc, lead, manganese, and chromium arsenate, forming microscopic, tabular crystals of an intense green color.
Properties
- Mohs hardness
- 2.5
- Luster
- Vitreous
- Streak
- Light green
- Density
- 4.45
- Cleavage
- Perfect on {0001}
- Fracture
- Brittle
- Transparency
- Transparent
- Crystal system
- Trigonal
Diagnostic features
## Identification Identification of puttapait is based on its characteristic, intensely emerald-green color, specific crystal form, and association with other rare minerals from the Puttapa mine. Due to its microscopic size, definitive confirmation requires advanced analytical methods, such as Raman spectroscopy or EDS analysis. ## Distinguishing from Similar Minerals It can be confused with other green, secondary arsenic minerals, such as mimetite or agardite, which may also occur at this locality. However, puttapait is distinguished by its unique, tabular crystal morphology forming rosettes. Other minerals of similar color rarely form such characteristic, hexagonal plates. ## Crystal Forms Crystals are very small, usually less than 0.5 mm in diameter. They take the form of thin, hexagonal or pseudohexagonal plates. They often coalesce into small, rosette-like aggregates on the surface of the host rock.
Geological environment
## Genesis Puttapaite is a secondary mineral that crystallizes in the oxidation zone of zinc-lead deposits. It forms as a result of the weathering of primary ore minerals (containing zinc, lead, and arsenic) in the presence of chromium, in a dry, desert climate. Its formation is associated with processes occurring within dolomitic rocks. ## Mineral Associations This mineral co-occurs with other rare secondary minerals characteristic of the Puttapa mine. It is most commonly found in association with willemite, hydrocerussite, mimetite, segnitite, gatehouseite, as well as iron and manganese oxides. ## Localities The only confirmed occurrence of puttapait in the world is its type locality – the Puttapa Zinc mine, located north of Beltana in the Flinders Ranges, South Australia.
Rarity
Extremely rare
For collectors
## Quality Criteria The most important criterion for evaluating a specimen is the quality and size of the crystals. The most prized specimens are those with well-formed, sharp, hexagonal crystals forming aesthetic, isolated rosettes on a contrasting matrix. The intensity of the emerald-green color also significantly increases its value. Due to the microscopic nature of the mineral, the photogenicity of the specimen (the possibility of taking a good microscopic photograph) is also crucial. ## Popular Localities All specimens available on the collector's market come from a single location – the Puttapa Zinc mine in South Australia. This is the only known occurrence of this mineral.
Care and storage
## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Due to the extreme delicacy and small size of the crystals, any mechanical contact (e.g., with a brush) or liquid cleaning is absolutely inadvisable and risks irreversible destruction of the specimen. ## What to Avoid Avoid contact with all chemicals, acids, and bases. Do not subject specimens to ultrasound. Store away from heat sources and protect from sudden temperature changes. ## Storage Puttapaite specimens should be stored under stable conditions, preferably in sealed "micromount" boxes, which protect them from dust, mechanical damage, and moisture. Avoid exposure to direct sunlight, although there is no evidence of fading.