Routhierite
Chemical formula: Tl<sup>1+</sup>Cu<sup>1+</sup>Hg<sup>2+</sup><sub>2</sub>As<sup>3+</sup><sub>2</sub>S<sup>2-</sup><sub>6</sub>
Routierite is a rare, metallic black mineral from the sulfosalt group, containing toxic elements: thallium, mercury, and arsenic.
Properties
- Mohs hardness
- 3-3.5
- Luster
- Metallic
- Streak
- Black
- Density
- 6.36
- Cleavage
- None
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Tetragonal
Diagnostic features
## Identification Routierite can be identified by its black color, strong metallic luster, and relatively high density. It occurs in a characteristic geological environment, in association with other rare sulfosalts containing thallium and mercury. Field identification is practically impossible and requires advanced analytical methods, such as chemical composition analysis (EDS/WDS). ## Distinguishing from Similar Minerals It can be confused with other black, metallic sulfosalts, such as pierrotite, lorandite, or wurtzite. Definitive differentiation requires chemical analysis to confirm the presence of the characteristic combination of elements: thallium, copper, mercury, and arsenic. ## Crystal Forms Crystals are usually small, tabular or short-prismatic, often exhibiting a square outline. They occur as single, well-formed crystals or as granular aggregates embedded in the host rock.
Geological environment
## Genesis Routierite is a low-temperature hydrothermal mineral. It forms in ore deposits where solutions rich in thallium, mercury, arsenic, and sulfur circulated. Its typical location is in mineral veins cutting through sedimentary rocks, such as dolomites and limestones. ## Mineral Associations This mineral co-occurs with other rare sulfosalts and sulfides. In its type locality (Jas Roux), it was found in association with pierrotite, stibnite, sphalerite, pyrite, realgar, orpiment, wurtzite, and raguinite. It most commonly occurs as inclusions within pierrotite. ## Localities The most important and type locality for routierite is the Jas Roux mine near La Chapelle-en-Valgaudémar, in the Hautes-Alpes department, France. This is the only confirmed and well-documented locality for this mineral worldwide.
Rarity
Extremely rare
For collectors
## Quality Criteria For collectors, the most important criterion is the presence of well-formed, sharp, and lustrous crystals, even if they are microscopic in size. Specimens where routierite is clearly visible against a contrasting matrix (e.g., light dolomite) are more highly valued. Due to its rarity, any analytically confirmed specimen has significant scientific and collectible value, regardless of its aesthetics. ## Popular Localities The only source of collectible specimens is the type locality – the Jas Roux mine in France. Material from this location is extremely rare on the market and sought after by specialized collectors of rare mineral species.
Care and storage
## Cleaning Due to its toxicity and brittleness, mechanical cleaning is strongly discouraged. If absolutely necessary, compressed air can be used to remove loose dust particles. Contact with water and any chemicals should be avoided. ## What to Avoid Contact of the mineral with skin, inhalation of dust, and ingestion must be strictly avoided. Thallium, mercury, and arsenic are highly toxic. The mineral should be protected from moisture, acids, and high temperatures. It should not be heated, as this may lead to the release of toxic fumes. ## Storage Routierite specimens must be stored in tightly sealed, clearly labeled containers (e.g., "perky box" type), away from children, pets, and food. It is recommended to store it separately from other minerals to avoid potential contamination. When handling the mineral, always use protective gloves and wash hands after each contact.