Aurihydrargyrumite
Chemical formula: Au<sub>6</sub>Hg<sub>5</sub>
Aurihydrargyrumite is an extremely rare natural amalgam of gold and mercury, forming tiny, metallic grains of tin-white or yellowish color.
Properties
- Mohs hardness
- 2.5
- Luster
- Metallic
- Streak
- Light yellow
- Density
- 16.52
- Cleavage
- None
- Fracture
- Hackly
- Transparency
- Opaque
- Crystal system
- Isometric
Diagnostic features
## Identification Key features for identifying aurihydrargyrumite are its exceptionally high density, metallic luster, low hardness, and malleability. The color, from silvery to yellowish, is also an important clue. However, definitive confirmation requires advanced analytical methods, such as X-ray microanalysis (EDS/WDS). ## Differentiation from Similar Minerals Aurihydrargyrumite can be confused with other natural amalgams (e.g., moschellandsbergite), native gold, or platinum. Native gold is usually more yellow and even denser. Platinum is harder. It can only be distinguished from other amalgams by chemical analysis. ## Crystal Forms This mineral primarily forms anhedral (irregular) grains and aggregates, rarely exceeding fractions of a millimeter in size. Very rarely, poorly formed, small crystals in the shape of cubes or octahedra are observed.
Geological environment
## Genesis Aurihydrargyrumite forms under low-temperature hydrothermal processes, most commonly in the oxidation (weathering) zones of gold deposits. It forms as a result of the reaction of mercury-bearing solutions with native gold. ## Mineral Associations This mineral often co-occurs with native gold, cinnabar (the main source of mercury), quartz, and other rare mercury minerals and amalgams. ## Localities The most important and type locality is the Kuranakh gold deposit on the Aldan Plateau (Sakha Republic, Russia). It has also been reported in several other locations worldwide, including the Chukotka region in Russia, but it remains an extremely rare mineral, known from only a few occurrences.
Rarity
Extremely rare
For collectors
## Quality Criteria In the case of such a rare micromineral, the collector's value is primarily determined by the richness of the specimen – i.e., the quantity and size of visible aurihydrargyrumite grains on the rock matrix. Specimens where this mineral clearly grows on native gold or occurs in association with well-formed cinnabar are also highly prized. Authenticity confirmed by analysis and accurate locality documentation are also crucial. ## Popular Localities Almost all specimens available on the collector's market come from the type locality – the Kuranakh deposit in Russia. These are usually small rock fragments with tiny, dispersed mineral grains.
Care and storage
## Cleaning The mineral is very soft and chemically sensitive. Cleaning should be kept to an absolute minimum. A soft brush or carefully applied compressed air can be used to remove dust. Avoid washing with water and any chemical agents. ## What to Avoid As a mercury amalgam, the mineral is potentially toxic. Direct skin contact should be avoided, and above all, inhalation of dust that might arise from damage to the specimen. It must not be heated, as this leads to the release of toxic mercury vapors. It should be protected from scratching, impacts, and contact with acids and other chemicals. ## Storage Aurihydrargyrumite specimens should be stored in a tightly sealed, stable container (e.g., a perky box) to minimize the risk of mercury vapor release and protect it from mechanical damage. It is advisable to place a warning label about toxicity on the container. Store away from other, harder minerals.