Zincospiroffite

Chemical formula: Zn₂+₂Te₄+₃O₈

Zincospiroffite is a very rare zinc tellurite, forming characteristic, small crystals of intense green color and adamantine luster.

## Characteristics Zincospiroffite is a mineral from the oxide group, specifically a zinc tellurite. It occurs as very small, tabular or prismatic crystals, rarely exceeding 1 mm. It also forms granular aggregates and coatings. Its most characteristic features are its intense, emerald-green to yellowish-green color and strong, almost adamantine luster, which makes it recognizable despite its small size. ## Physical Properties This mineral is characterized by a hardness of approximately 3.5 on the Mohs scale. It has a very high density of 5.75 g/cm³, which is unusual for minerals with a non-metallic appearance. It is brittle, and its crystals exhibit perfect cleavage in one direction. The luster is strongly vitreous to adamantine. It is transparent to translucent. ## Colors and Varieties Zincospiroffite occurs in shades from emerald-green, through bottle-green, to yellowish-green. No color or commercial varieties are distinguished. ## History and Name The mineral was discovered in the Old Guard Mine in Tombstone, Cochise County, Arizona (USA). It was described in 1995 by George Y. Chao, Joseph A. Taggart Jr., and Andrew C. Roberts, who is also a co-discoverer of spiroffite. The name refers to its chemical composition (zinc) and its structural and chemical similarity to the mineral spiroffite. ## Uses Zincospiroffite has no industrial application. Its significance is purely scientific and collectible; it is valued by collectors specializing in rare minerals (so-called micromounts).

Properties

Mohs hardness: 3.5
Luster: Adamantine to vitreous
Streak: Light green
Density: 5.75
Cleavage: Perfect on {001}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Tetragonal

Diagnostic features

## Identification Key features for identifying zincospiroffite include: intense green color, very strong adamantine luster, high density, and co-occurrence with other rare tellurites and tellurides. Due to the size of the crystals, a microscope is essential for its observation and identification. ## Distinguishing from Similar Minerals Zincospiroffite can be confused with other green, secondary zinc or copper minerals. It differs from malachite by its much stronger luster and crystal habit. It differs from other rare tellurites (e.g., spiroffite, which is colorless to white) by its characteristic green color. Final confirmation requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical composition analysis (EDS). ## Crystal Forms Zincospiroffite crystals are most often tabular, flattened parallel to the cleavage plane, or short-prismatic. They usually form small, scattered groups or individual crystals grown on the host rock.

Geological environment

## Genesis Zincospiroffite is a secondary mineral, formed in the oxidation (weathering) zones of ore deposits containing tellurium and zinc. It forms under low temperature and pressure conditions as a result of the alteration of primary tellurides. ## Mineral Associations This mineral co-occurs with other, often equally rare, oxides and tellurites. It is most commonly associated with: quartz, tellurium, tellurite, spiroffite, paratellurite, emmonsite, mcalpineite, frankhawthorneite, and various iron and manganese oxides. ## Localities Zincospiroffite is an extremely rare mineral. Besides its type locality – the Old Guard Mine in Tombstone, Arizona (USA) – its occurrence has been confirmed in only a few other places worldwide, including the Bambolla Mine in Moctezuma, Mexico, and the Kawazu Mine in Japan. All these localities are known for their exceptional tellurium mineralization.

Rarity

Very rare

For collectors

## Quality Criteria The most highly valued zincospiroffite specimens are those with sharply terminated, well-formed, and transparent crystals of intense, emerald-green color. Contrast with the rock matrix and the presence of associated minerals are important. Due to the microscopic size of the crystals, their quality and photogenicity under magnification are crucial. Crystal size, even if it exceeds 0.5 mm, significantly increases the value of the specimen. ## Popular Localities The most sought-after specimens by collectors come from the type locality in Tombstone, Arizona, USA. These are considered classic and serve as the standard for this mineral.

Care and storage

## Cleaning Zincospiroffite specimens are extremely delicate and small. Cleaning should be kept to an absolute minimum. If necessary, compressed air (from a safe distance) can be used to remove dust. Avoid contact with water and any chemicals. ## What to Avoid The mineral is brittle and has perfect cleavage, making it very susceptible to mechanical damage, shocks, and vibrations. Ultrasonic cleaners, all acids, and detergents should be avoided. It should not be heated or exposed to sudden temperature changes. ## Storage It is recommended to store specimens exclusively in specialized micromount boxes, which protect them from dust, moisture, and mechanical damage. Display should be done under a microscope.

Sources

IMA Mineral List (CNMNC)