Kleinite
Chemical formula: (Hg<sub>2</sub>N)<sup>1+</sup>(Cl,S<sup>6+</sup>O<sub>4</sub>)·nH<sub>2</sub>O
Kleinite is a rare, photosensitive mercury mineral with a characteristic canary-yellow color, darkening upon exposure to light.
Properties
- Mohs hardness
- 3.5
- Luster
- Adamantine
- Streak
- Yellow
- Density
- 7.9-8.0
- Cleavage
- Perfect on {0001}
- Fracture
- Conchoidal
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
Diagnostic features
## Identification Key diagnostic features include canary-yellow color, hexagonal crystal habit, adamantine luster, and very high density. The most important test is observing the color change (darkening) under light. ## Distinguishing from Similar Minerals It can be confused with other yellow secondary minerals from oxidation zones, such as terlinguaite or eglestonite, which often co-occur with it. It is distinguished from them by its characteristic hexagonal crystal shape and distinct photosensitivity. It differs from native sulfur by its significantly higher density and crystal form. ## Crystal Forms It forms well-developed, hexagonal crystals with prismatic, tabular, or bipyramidal habit. It also occurs as granular aggregates and powdery coatings.
Geological environment
## Genesis Kleinite is a secondary mineral, forming in the oxidation zones of mercury deposits. It crystallizes in dry, desert conditions from solutions rich in mercury, chlorine, and sulfates. ## Mineral Associations It most often co-occurs with other mercury minerals, such as native mercury, calomel, terlinguaite, montroydite, eglestonite, as well as with gypsum, calcite, and barite. ## Localities The most important and classic locality, from which the best specimens originate, is the Terlingua district in Brewster County, Texas (USA), especially in the Mariposa and Perry mines. It is also known from the McDermitt mine in Humboldt County, Nevada (USA), and from several locations in Germany (e.g., in Palatinate).
Rarity
Rare
For collectors
## Quality Criteria The most highly valued specimens are those with well-formed, sharp, transparent crystals of intense, canary-yellow color that have not yet been darkened by light. The aesthetic composition on the matrix and association with other rare mercury minerals are also important. ## Popular Localities Specimens from the historical localities in the Terlingua district, Texas, are by far the most sought after by collectors.
Care and storage
## Cleaning Strictly avoid wet cleaning, especially with water, which can react with the mineral. Only gentle dust removal with a soft brush or compressed air from a safe distance is permissible. ## What to Avoid Exposure to sunlight and intense artificial lighting, which causes irreversible darkening of the mineral, must be strictly avoided. Avoid high temperatures, which can lead to its decomposition and the release of toxic mercury vapors. Protect from all chemicals. Due to the high toxicity of mercury, direct skin contact, dust inhalation, and always washing hands after contact with the specimen should be avoided. ## Storage Kleinite specimens must be stored in complete darkness, preferably in a sealed, padded box, to prevent light exposure and accidental damage. The box should be clearly labeled as containing a toxic mercury mineral.