Carmeltazite
Chemical formula: Zr<sup>4+</sup>Al<sub>2</sub>Ti<sup>3+</sup><sub>4</sub>O<sub>11</sub>
A newly discovered oxide of zirconium, aluminum, and titanium, found in Israel, distinguished by its almost black color and metallic luster.
Properties
- Mohs hardness
- >8
- Luster
- Metallic
- Streak
- Dark brown
- Density
- 4.122
- Cleavage
- Good on {100}, {010}, and {001}
- Transparency
- Opaque
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Identification of carmeltazite is impossible without advanced laboratory equipment. It requires analysis by X-ray diffraction (XRD) and electron microprobe (EMPA) to confirm its crystal structure and chemical composition. Visually, it appears as microscopic, black, metallic inclusions in corundum. ## Distinguishing from Similar Minerals It can be confused with other opaque, dark inclusions in corundum, such as ilmenite, rutile, or hematite. Differentiation requires specialized chemical and structural analysis. ## Crystal Forms It forms small, elongated crystals with a prismatic habit, occurring as single inclusions or small aggregates within corundum crystals.
Geological environment
## Genesis It originates from Cretaceous volcanic pyroclastic rocks found in the Kishon River area on Mount Carmel. It formed under high pressure and temperature conditions in deep layers of the Earth's crust or in the upper mantle, and was then transported to the surface by volcanic processes. The mineral crystallized directly from melts trapped within growing corundum crystals. ## Mineral Associations It is inextricably associated with corundum (sapphire). It is also accompanied by titanite, anorthite, and the newly discovered mineral tistarite (Ti₂O₃). ## Localities The only confirmed locality in the world is Mount Carmel in northern Israel.
Rarity
Extremely rare
For collectors
## Quality Criteria The quality of a carmeltazite specimen is, in fact, the quality of the surrounding corundum (sapphire). The most valuable specimens are those in which carmeltazite inclusions are relatively large (though still microscopic), clearly visible under a microscope, and well-formed. Scientific confirmation of the mineral's presence is key. ## Popular Localities The only source of specimens is the type locality – Mount Carmel in Israel. Specimens from this location containing confirmed carmeltazite are highly sought after by specialized institutions and collectors of rare minerals.
Care and storage
## Cleaning Due to its microscopic occurrence (inclusions in corundum), the host specimens (corundum) can be cleaned using standard methods, such as ultrasonics or steam. Carmeltazite itself does not require separate cleaning. ## What to Avoid As a hard oxide, it is chemically and physically very resistant. However, aggressive acids (e.g., hydrofluoric acid) should be avoided, as they could damage both the inclusions and the surrounding corundum. ## Storage Specimens containing carmeltazite should be stored like typical corundum specimens – in separate boxes or on stands to prevent scratching other, softer minerals. It is not sensitive to light or moisture.