Dinilawiite

Chemical formula: [Pb<sup>2+</sup><sub>4</sub>OAl(OH)<sub>6</sub>]<sub>2</sub>(S<sup>6+</sup>O<sub>3</sub>S<sup>2-</sup>)<sub>2</sub>·(S<sup>6+</sup>O<sub>3</sub>S<sup>2-</sup>)(H<sub>2</sub>O)<sub>5</sub>

Dinilawiite is an extremely rare, newly discovered mineral with a complex chemical composition, forming microscopic, yellow tabular crystals.

## Characteristics Dinilawiite is a very rare mineral from the sulfate group, distinguished by an exceptionally complex chemical formula containing lead, aluminum, sulfur in various oxidation states, and water. It occurs as extremely small, hexagonal crystals with a tabular habit, not exceeding 50 micrometers in diameter and 5 micrometers in thickness. These crystals form rosette-like or irregular aggregates on the surface of other minerals. ## Physical Properties Due to the microscopic size of the crystals, most physical properties, such as hardness, density, or fracture, have not been precisely determined. The mineral's luster is described as pearly to vitreous. It is transparent. ## Colors and Varieties Dinilawiite has a characteristic, light yellow color. The streak is light yellow. No varieties have been distinguished. ## History and Name The mineral was officially approved by the International Mineralogical Association (IMA) in 2023 under number IMA2023-030. Its name honors Dr. Dini L. Ramdanil, an Indonesian geologist from the Center for Mineral, Coal and Geothermal Resources in Bandung, in recognition of his contribution to geological research in Indonesia. It was discovered in the fumarole area of Papandayan volcano. ## Applications Dinilawiite has no industrial application. Its significance is purely scientific and collectible, as a unique and newly described mineral species.

Properties

Luster
Pearly to Vitreous
Streak
Light yellow
Transparency
Transparent
Crystal system
Trigonal

Diagnostic features

## Identification Identification of dinilawiite is possible only through advanced analytical methods, such as Raman spectroscopy and chemical analysis using an electron microprobe (EDS/WDS). Visually, under high magnification, characteristic, light yellow, hexagonal plates forming rosette-like clusters can be observed. ## Distinguishing from Similar Minerals It can be confused with other secondary yellow sulfates that form in volcanic environments, such as jarosite or alunogen. Final differentiation requires specialized instrumental analysis, which allows for the identification of dinilawiite's unique chemical composition. ## Crystal Forms The mineral forms very small, thin, tabular crystals with a hexagonal outline. These crystals often combine into small, rosette-like or irregular aggregates.

Geological environment

## Genesis Dinilawiite is a mineral of volcanic origin, formed by sublimation from volcanic gases near active fumaroles. It crystallizes at high temperatures (around 150-200°C) in an environment rich in sulfur and heavy metals, directly on the surface of volcanic rocks. ## Mineral Associations It co-occurs with other rare fumarolic minerals, such as eliasite-(La) and papandayanite. These minerals form under similar conditions, precipitating from hot volcanic gases. ## Localities The only confirmed locality of dinilawiite in the world is its type locality – the fumaroles of Kawah Mas crater on Papandayan volcano, West Java province, Indonesia.

Rarity

Extremely rare

For collectors

## Quality Criteria As a micromount mineral, the quality of a specimen is primarily determined by the richness and aesthetics of the crystal aggregates visible under the microscope. Specimens with clearly formed, undamaged, rosette-like clusters of yellow crystals, contrasting well with the matrix, are most valued. Crystal size, although always microscopic, is also important – larger plates are more desirable. ## Popular Localities The only source of specimens is the type locality in Indonesia, which makes each specimen from this location unique.

Care and storage

## Cleaning Dinilawiite specimens are extremely delicate due to the microscopic size of the crystals. Mechanical or chemical cleaning is not recommended. Any attempts at cleaning may irreversibly destroy the mineral. It should be treated solely as a micromount specimen. ## What to Avoid Avoid contact with water, chemicals, ultrasound, and any vibrations or impacts. Changes in temperature and humidity can be harmful. Do not expose the specimen to direct sunlight. ## Storage Dinilawiite specimens should be stored exclusively in specialized micromount boxes, under stable room conditions, away from dust, moisture, and sources of vibration. Handling the specimen requires great care.

Sources

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