Griffinite

Chemical formula: Al₂Ti⁴⁺O₅

Griffinite is a rare aluminum and titanium oxide, forming microscopic, prismatic crystals in specific metamorphic environments.

## Characteristics Griffinite is a mineral from the oxide group, chemically classified as an aluminum and titanium oxide. It occurs as very small, elongated, prismatic crystals, rarely exceeding 100 micrometers in length. It typically forms inclusions within other minerals, primarily corundum. Due to the microscopic size of the crystals, its visual features are difficult to observe without specialized equipment. ## Physical Properties Griffinite crystals exhibit a submetallic luster. They are opaque. Hardness and density have not been precisely measured due to the small size of the samples, but the Mohs hardness is estimated to be around 7, and the density calculated based on chemical composition and unit cell parameters is 3.73 g/cm³. ## Colors and Varieties Griffinite has a dark gray color. No color varieties or commercial varieties are known. ## History and Name The mineral was approved by the International Mineralogical Association (IMA) in 2022. Its name honors William "Bill" Griffin, an Australian geologist and professor at Macquarie University, for his contributions to geochemistry and petrology of the Earth's mantle. It was discovered in samples from Mount Carmel in Israel. ## Applications Griffinite has no industrial or commercial applications. Its significance is purely scientific and collectible, especially for collectors specializing in microminerals or minerals from the type locality.

Properties

Mohs hardness
7
Luster
Sub-Metallic
Streak
Dark gray
Density
3.73
Cleavage
Good on {010}
Fracture
Uneven
Transparency
Transparent
Crystal system
Orthorhombic

Diagnostic features

## Identification Identification of griffinite is impossible without advanced analytical techniques. It requires the use of a scanning electron microscope (SEM) with chemical composition analysis (EDS) and X-ray diffraction (XRD) to confirm the crystal structure. A characteristic feature is its chemical composition (aluminum and titanium oxide) and its co-occurrence with other rare minerals in the specific environment of Mount Carmel. ## Distinguishing from Similar Minerals Griffinite can be confused with other titanium oxides, such as rutile or anatase, which may occur in similar parageneses. Differentiation relies solely on precise chemical analysis, which shows the presence of aluminum as a major component alongside titanium, and on structural analysis. ## Crystal Forms Griffinite forms elongated, prismatic crystals with a nearly square cross-section. The crystals are very small, reaching a maximum of 100 micrometers in length and 30 micrometers in width.

Geological environment

## Genesis Griffinite forms under conditions of high-temperature, low-pressure contact metamorphism. Its formation is associated with the entrapment of volcanic melts within volcanic rocks. It crystallizes from residual melts rich in titanium and aluminum in closed cavities within corundum. ## Mineral Associations This mineral occurs in close association with corundum (sapphire), spinel, anorthite, hibonite, grossite, as well as with very rare minerals discovered in the same locality, such as tistarite and carmeltazite. ## Localities The only confirmed occurrence of griffinite in the world is Mount Carmel in northern Israel. This is its type locality.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of a griffinite specimen is primarily assessed based on its scientific confirmation and documentation. Since the crystals are microscopic, the quality of the microscopic image and analytical data accompanying the specimen is paramount. The presence of well-formed crystals, even if visible only under high magnification, and their association with other rare minerals from this locality, enhance their attractiveness. ## Popular Localities The only source of griffinite is its type locality – Mount Carmel in Israel. Specimens from this location are highly valued by collectors specializing in rare minerals and micromounts.

Care and storage

## Cleaning Due to the extremely small size of the crystals and their occurrence as inclusions in the host rock, cleaning individual griffinite specimens is not practical. The host specimen can be cleaned with compressed air to remove dust. ## What to Avoid Avoid contact with strong acids and ultrasonic cleaners, which could damage both the microscopic griffinite crystals and the surrounding minerals. Samples should be protected from impacts and abrasion. ## Storage Griffinite specimens, typically microminerals, are best stored in specialized "micromount" boxes, which protect them from dust and mechanical damage. The label should include the exact location and mineral identification.

External references

Sources

Read more