Dagenaisite

Chemical formula: Zn²⁺₃Te⁶⁺O₆

Dagenaisite is a very rare zinc tellurate, forming microscopic, transparent crystals with a characteristic green or greenish-gray color.

## Characteristics Dagenaisite is a hydrated zinc tellurate, occurring as very small, bladed or tabular crystals, rarely exceeding 0.2 mm in length. It typically forms small aggregates or rosettes. It is a secondary mineral, forming in the oxidation zones of tellurium ores. ## Physical Properties This mineral is extremely soft, with a Mohs hardness of 1-2. It is relatively dense for a non-metallic mineral, with a specific gravity of approximately 6.0 g/cm³. Crystals are transparent to translucent and exhibit a white streak. The fracture is uneven. ## Colors and Varieties Dagenaisite occurs in shades of green, from light green to greenish-gray. No varieties have been distinguished. ## History and Name The mineral is named in honor of Michel Dagenais (born 1942), a Canadian mineral collector from Montreal, who specializes in minerals from Mont Saint-Hilaire and provided many new or rare species for study. The mineral was approved by the IMA in 2011. ## Uses Due to its extreme rarity and microscopic size, dagenaisite has no industrial application and is solely an object of scientific interest and a collector's item for specialized micromineral collectors.

Properties

Mohs hardness
0-2
Streak
white
Density
6.0
Fracture
Irregular/Uneven
Transparency
Transparent,Translucent
Crystal system
Monoclinic

Diagnostic features

## Identification Identification of dagenaisite in practice is impossible without advanced analytical methods, such as Raman spectroscopy or chemical analysis (EDS). Preliminary identification based on appearance is difficult due to the microscopic size of the crystals. Its green color and co-occurrence with other rare tellurates at the locality can be a clue. ## Distinguishing from Similar Minerals It can be confused with other secondary, green zinc or copper minerals, such as malachite, brochantite, or other rare tellurates. Final differentiation requires chemical analysis to confirm the presence of tellurium and zinc and the absence of copper. ## Crystal Forms It forms very small, bladed or tabular crystals, often grouped into rosette aggregates or chaotic clusters.

Geological environment

## Genesis Dagenaisite is a secondary mineral, formed in the oxidation zones of ore deposits rich in tellurium. It forms as a result of the weathering of primary tellurides in the presence of zinc minerals. ## Mineral Associations At the type locality (Gold Chain mine), it co-occurs with other rare tellurates and tellurides, such as zincospiroffite, spiroffite, jensenite, as well as tenorite, quartz, and barite. ## Localities The only confirmed locality of dagenaisite in the world is its type locality: the Gold Chain mine in the Tintic mining district, Juab County, Utah, USA.

Rarity

Extremely rare

For collectors

## Quality Criteria For micromineral collectors, the most desirable specimens are those with well-formed, sharp crystals, forming aesthetic groups or rosettes. The intensity of the green color and the abundance of associated minerals on the rock matrix also increase the value of the specimen. ## Popular Localities All known collector specimens come from a single location in the world - the Gold Chain mine in Utah, USA. This is the locality from which the best and only available samples of this mineral originate.

Care and storage

## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Due to extreme softness and fragility, any mechanical contact, including with brushes or water, should be avoided. ## What to Avoid Contact with water, chemicals, ultrasound, and sudden temperature changes must be strictly avoided. The mineral is very soft and easily susceptible to mechanical damage. ## Storage Dagenaisite specimens, as microminerals, should be stored in specialized "micromount" boxes that protect them from dust, shocks, and mechanical damage. Exposure to moisture should be avoided.

External references

Sources

Read more