Kadyrelite

Chemical formula: ([Hg¹⁺]₂)₃OBr₃(OH)

Kadyrelite is a very rare mercury oxyhalide, forming microscopic, yellow crystals in the oxidation zones of mercury deposits.

## Characteristics Kadyrelite is a mineral from the oxyhalide group, chemically a complex mercury(I) oxybromohydroxide. It occurs as very small, tabular or prismatic crystals, rarely exceeding 0.5 mm. Most often, it forms thin coatings, granular aggregates, or appears as single, dispersed crystals on the host rock. Its characteristic feature is an intense, lemon-yellow to orange-yellow color. ## Physical Properties Kadyrelite crystals exhibit an adamantine to greasy luster. The mineral is transparent to translucent. Due to the microscopic size of the crystals, hardness and density have not been precisely measured. The calculated density is approximately 8.65 g/cm³, which is a very high value, typical for mercury minerals. ## Colors and Varieties This mineral is monochromatic, taking on shades from lemon-yellow, through golden-yellow, to orange-yellow. No color varieties or commercial varieties are distinguished. ## History and Name Kadyrelite was discovered in the Kadyrel mercury deposit in the Tuva Republic, Russia. It was described and approved as a new mineral by the International Mineralogical Association (IMA) in 1987. The mineral's name comes directly from its discovery location (type locality). ## Uses Kadyrelite has no industrial application. Its significance is purely scientific and collectible, as a unique and rare representative of secondary mercury minerals.

Properties

Mohs hardness: 2.5-3
Color: Bright to dull orange
Luster: Adamantine to greasy
Streak: Orange-yellow
Density: 0
Cleavage: None
Fracture: Irregular/Uneven,Conchoidal
Transparency: Transparent
Crystal system: Isometric

Diagnostic features

## Identification Kadyrelite is identified by its characteristic, intense yellow color, very high density (if measurable), adamantine luster, and occurrence in paragenesis with other secondary mercury minerals. Due to the size of the crystals, final identification requires advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS). ## Distinguishing from Similar Minerals Kadyrelite can be confused with other secondary, yellow mercury minerals, such as terlinguaite, eglestonite, or poyarkovite. Distinguishing it with the naked eye is practically impossible and requires laboratory analysis. Co-occurrence with calomel (white or gray) and native mercury (silvery globules) can be a diagnostic clue. ## Crystal Forms Kadyrelite crystallizes in the isometric system. It forms very small, tabular crystals with hexagonal or octagonal outlines, as well as short prismatic crystals. Most often, it occurs as fine-grained aggregates, coatings, and crusts on other minerals.

Geological environment

## Genesis Kadyrelite is a secondary mineral, forming in the oxidation (supergene) zones of mercury deposits. It forms as a result of the weathering of primary mercury sulfides (mainly cinnabar) in the presence of bromine-rich solutions. This process occurs under conditions of low temperatures and pressures, close to the Earth's surface. ## Mineral Associations This mineral co-occurs with other secondary mercury minerals. Its most common associates are calomel (Hg₂Cl₂), native mercury (Hg), kuznetsovite (As₂O₃·Hg₃SO₄Cl₂), shakhovite (Hg₄SbO₃(OH)₃), poyarkovite (Hg₃OCl), and primary cinnabar (HgS). ## Localities The most important and type locality for kadyrelite is the Kadyrel mercury deposit in the Tuva Republic, Russia. This is the only confirmed and well-documented locality for this mineral in the world.

Rarity

Very rare

For collectors

## Quality Criteria The collectible appeal of kadyrelite primarily depends on the visibility and quality of the microcrystals. Specimens with well-formed, sharp crystals of an intense, lemon-yellow color, contrasting with the rock matrix, are most valued. Rich aggregates and coatings are more desirable than single, dispersed crystals. Due to its rarity, every well-documented specimen has significant value for specialized collectors. ## Popular Localities The only source of kadyrelite specimens is its type locality – the Kadyrel deposit in Russia. All specimens available on the collector's market originate from this single location.

Care and storage

## Cleaning Kadyrelite specimens should generally not be wet cleaned. Due to its microscopic nature and potential reactivity, it is best to remove dust with a soft brush or a photographic air blower. Avoid contact with water and any chemicals. ## What to Avoid Absolutely avoid contact with acids and other chemicals, which can decompose it. The mineral is sensitive to high temperatures. As a mercury mineral, it is toxic – avoid inhaling dust and wash hands after any contact with the specimen. ## Storage Kadyrelite specimens should be stored in closed, airtight containers (e.g., "perky box" type) to limit contact with air and moisture and prevent accidental abrasion of microcrystals. Store away from sunlight, in a dry and cool place. It is necessary to clearly label the specimen as toxic.