Tedhadleyite

Chemical formula: Hg²⁺Hg¹⁺₁₀O₄I¹⁻₂(Cl,Br)₂

Tedhadleyite is an extremely rare mercury, iodine, and chlorine mineral, forming dark red to black, opaque crystals with a strong luster.

## Characteristics Tedhadleyite is a very complex mercury oxyhalide, occurring as small, tabular or prismatic crystals, rarely exceeding 1 mm in length. Its color ranges from dark red to black, and due to its high mercury content, it is an opaque mineral or only translucent on its thinnest edges. It exhibits a strong, almost metallic luster. ## Physical Properties This mineral is characterized by an adamantine to submetallic luster. It is translucent to opaque. Due to its extreme rarity and small crystal size, its hardness and density have not been precisely measured. ## History and Name Tedhadleyite was discovered in 1996 and described as a new mineral species. Its name honors Ted Hadley (1926-1997), an American micromineral collector who first found this mineral. The discovery was made at the Clear Creek claim in the Goat Mountain area (San Benito County, California, USA).

Properties

Luster
Adamantine to submetallic
Streak
Red
Density
0
Cleavage
Poor {010}
Fracture
Irregular/Uneven
Transparency
Translucent,Opaque
Crystal system
Triclinic

Diagnostic features

## Identification Key diagnostic features include its dark red to black color, strong adamantine or submetallic luster, red streak, and occurrence as very small, tabular crystals. Its association with other rare mercury minerals at the locality is also an important clue. ## Distinguishing from Similar Minerals It can be confused with cinnabar (HgS), which also has a red color and streak, but typically forms differently shaped crystals and has a lower luster. Other rare, red mercury minerals from this locality (e.g., eglestonite) require advanced analytical methods for certain identification. ## Crystal Forms Tedhadleyite forms very small, tabular or short prismatic crystals, often grouped into small aggregates.

Geological environment

## Genesis Tedhadleyite forms under low-temperature hydrothermal conditions, in mercury-rich serpentinites. It is a product of the alteration of pre-existing mercury minerals in the presence of solutions rich in chlorine, bromine, and iodine. ## Mineral Associations It co-occurs with other rare mercury minerals, such as native mercury, cinnabar, calomel, eglestonite, wattersite, kuznetsovite, and shuvalovite. ## Localities The only confirmed locality for tedhadleyite in the world is its type locality: Clear Creek claim, in the Goat Mountain area, San Benito County, California, USA. This is one of the world's most famous sites for rare mercury minerals.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a specimen primarily depends on the size and habit of the crystals, which is a rarity. Specimens with distinct, sharp crystals of intense, dark red color, contrasting with the rock matrix, are most valued. The presence of other rare associated minerals is also important. ## Popular Localities All known specimens come from a single location worldwide – the Clear Creek deposit in California, USA. This locality is closed to public collecting, making historical material the only available on the market.

Care and storage

## Cleaning Due to its extreme rarity and potential toxicity, cleaning is not recommended. Specimens should be left undisturbed. If absolutely necessary, compressed air can be used to remove dust. ## What to Avoid Avoid contact with water, chemicals, acids, and ultrasonics. The mineral is sensitive to temperature changes and direct sunlight. Due to its mercury content, avoid inhaling dust and direct skin contact. ## Storage Tedhadleyite specimens must be stored in sealed, stable containers (e.g., "perky boxes"), away from light, moisture, and heat sources. They should be kept away from other minerals that could react with them, and absolutely out of reach of children and pets.

External references

Sources

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