Teineite
Chemical formula: Cu<sup>2+</sup>Te<sup>4+</sup>O<sub>3</sub>·2H<sub>2</sub>O
A rare copper and tellurium mineral, forming characteristic blue prismatic or acicular crystals.
Properties
- Mohs hardness
- 2.5
- Luster
- Vitreous
- Streak
- Light blue
- Density
- 3.79 - 3.81
- Cleavage
- Perfect on {101}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Key diagnostic features of teineite are its characteristic blue color, crystal habit (elongated prisms, needles), low hardness (2.5 on the Mohs scale), and specific occurrence environment. Co-occurrence with other tellurium minerals is a strong indicator. ## Distinguishing from Similar Minerals Teineite is sometimes confused with other blue secondary minerals: - **Chalcanthite**: It is water-soluble, teineite is not. - **Linarite**: Has a similar color but is significantly denser and often forms crystals of a different shape. - **Azurite**: Reacts with hydrochloric acid, releasing gas bubbles, which teineite does not. - **Chrysocolla**: Usually occurs in amorphous or botryoidal forms and rarely forms distinct crystals. ## Crystal Forms Teineite crystals are prismatic, often elongated and acicular. They usually occur as radial or tangled aggregates, as well as druses lining rock fissures.
Geological environment
## Genesis Teineite is a secondary mineral, forming in the oxidation zones of hydrothermal ore deposits that are rich in both copper and tellurium. It forms as a result of the weathering of primary copper tellurides and sulfides. ## Mineral Associations It most commonly co-occurs with minerals such as native tellurium, quartz, barite, pyrite, bornite, tetrahedrite, and other rare tellurites and tellurates, e.g., emmonsite, mackayite, or balangeroite. ## Localities The most important and historical locality is the Teine mine in Hokkaido, Japan, from which the best specimens originate. It is also known from several locations in the United States (e.g., Baker mine in California; Tombstone in Arizona) and from Moctezuma in Sonora, Mexico.
Rarity
Rare
For collectors
## Quality Criteria The most highly prized teineite specimens are those with well-formed, sharply terminated crystals of intense blue color. The aesthetic arrangement of crystals on a small rock matrix is also of great importance. Specimens from the type locality (Teine mine) and those that occur in association with other rare tellurium minerals are particularly sought after. ## Popular Localities Classic and most desired by collectors specimens come from the Teine mine in Japan. Good quality material, often in the form of rich druses, is also supplied by deposits in the Moctezuma region of Mexico.
Care and storage
## Cleaning Teineite specimens are very delicate and should be handled with care. To remove dust, it is best to use a soft brush or a photographic air blower. If necessary, the specimen can be very briefly rinsed in distilled water and immediately, gently dried. Ultrasonic cleaners should be avoided. ## What to Avoid The mineral is soft and susceptible to scratching. It should be protected from contact with harder minerals. As a hydrated mineral, it is sensitive to high temperatures, which can cause dehydration and destruction. Exposure to chemicals and acids should be avoided. Prolonged exposure to direct sunlight may not be advisable. ## Storage It is recommended to store teineite specimens in separate, sealed boxes (e.g., "micromount" type) to protect them from dust, mechanical damage, and sudden changes in humidity.