Hexathioplumbite

Chemical formula: [Pb₂+₄(OH)₄]Pb₂+(S₆+O₃S₂-)₃

Hexathioplumbite is an extremely rare lead mineral, a sulfate-sulfide, discovered in the Kombat Mine in Namibia.

## Characteristics Hexathioplumbite is a lead mineral from the sulfate-sulfide group, distinguished by its unique chemical composition. It forms very small, hexagonal, tabular crystals, reaching up to 0.1 mm in size. It occurs as single crystals or small aggregates on a substrate. Due to its extreme rarity and small crystal size, its full visual characterization is limited to microscopic observations. ## Physical properties Hexathioplumbite crystals exhibit a luster described as submetallic to adamantine. They are transparent to translucent. Due to the microscopic size of the crystals, hardness and density have not been measured, but only calculated based on composition and crystal structure. The calculated density is approximately 6.55 g/cm³. ## Colors and varieties This mineral has a characteristic, bright, yellow-orange color. No varieties are known. ## History and name The name "hexathioplumbite" refers to its hexagonal crystallographic system (hexa-), sulfur content (-thio-), and lead (-plumb-), which is its main component. It was first described in 2018 by G. Giester, Ch. L. Lena, B. R. M. Adiwidjaja, and J. Schlüter based on material collected at the Kombat Mine in Namibia. It was approved by the International Mineralogical Association (IMA) under number IMA 2017-091. ## Applications Hexathioplumbite has no practical or commercial applications. Its significance is purely scientific and as a collector's item, as a unique and newly discovered mineral species.

Properties

Luster: Sub-Adamantine, Sub-Metallic
Streak: Yellow
Density: 6.55
Transparency: Transparent to translucent
Crystal system: Hexagonal

Diagnostic features

## Identification Field identification of hexathioplumbite is practically impossible. Identification requires specialized laboratory equipment. Suggestive features (observed under a microscope) may include: bright yellow-orange color, hexagonal crystal shape, and occurrence in the specific mineral environment of the Kombat Mine. ## Differentiation from similar minerals Many other secondary lead minerals, such as mimetite or wulfenite, may have a similar color. Hexathioplumbite differs from them by its unique, hexagonal tabular habit on a micro-scale and its paragenesis. Final differentiation is only possible using advanced analytical methods, such as X-ray diffraction (XRD) or spectroscopy. ## Crystal forms The mineral forms very small, thin, hexagonal (six-sided) tabular crystals. They occur as single, isolated plates or small, loose aggregates on the surface of the host rock.

Geological environment

## Genesis Hexathioplumbite is a secondary mineral that formed in the oxidation zone of a polymetallic (copper-lead-silver) deposit in the Kombat Mine. Its formation is the result of complex weathering processes of primary sulfide minerals in an environment rich in lead and sulfates, within carbonate rocks (dolomites). ## Mineral associations At its type locality, hexathioplumbite occurs in association with other rare secondary minerals, such as: anglesite, queitite, kombatite, and newly discovered minerals like ludlockite and namibite. It also co-occurs with calcite. ## Localities The only known occurrence (type locality) of hexathioplumbite in the world is the Kombat Mine, located in the Otjozondjupa region, near Grootfontein in Namibia.

Rarity

Extremely rare

For collectors

## Quality criteria The quality of a hexathioplumbite specimen is assessed solely based on microscopic criteria. Specimens with well-formed, sharp, undamaged crystals of intense, yellow-orange color are most highly valued. The aesthetic arrangement of crystals on the matrix and their size are also important – the larger they are (even if only fractions of a millimeter), the more valuable. The presence of associated minerals can enhance the scientific and visual value of the specimen. ## Popular localities The only source of hexathioplumbite specimens is the Kombat Mine in Namibia. This is one of the most renowned mineralogical localities in the world, famous for the occurrence of many rare and unique secondary minerals, which makes specimens from there particularly sought after by specialized collectors.

Care and storage

## Cleaning Due to the extreme rarity, small size, and delicacy of the crystals, hexathioplumbite specimens should not be cleaned by any mechanical or chemical means. Any attempt at cleaning risks irreversible destruction of the mineral. They should be treated solely as objects for microscopic observation. ## What to avoid Avoid any contact with chemicals, water, ultrasound, and sudden temperature changes. The crystals are extremely small and brittle, susceptible to mechanical damage from the slightest touch. They should be protected from dust and vibrations. ## Storage Hexathioplumbite specimens must be stored under stable conditions, in specialized, sealed "micromount" boxes that protect against dust, shocks, and physical contact. Display should only occur under a microscope, without removing the specimen from its protective container.

Sources

IMA Mineral List (CNMNC)