Tolliametile

Tolliametile is a rare mineral species described from the Tollia region in the northern part of the mountain belt. It is notable for its metallic to pearly luster and an iridescent color range that spans olive-green to bronze, with crystals typically occurring as small, well-formed prisms in high-grade metamorphic rocks.

Discovery and naming: Tolliametile was first identified in 1983 by a mineralogical survey led by researchers exploring metamorphic terrains in the Tollia region. The name combines the locality, Tollia, with the suffix -tile, a common convention in mineral nomenclature for newly described silicate-like minerals.

Occurrence and geology: The mineral forms in contact metamorphic zones within granulite facies gneisses and pegmatitic pockets. It is often found alongside garnet, sillimanite, cordierite, and magnetite, and occurs as isolated crystals up to several centimeters in length. The geological context suggests formation under high-temperature, moderate-pressure conditions typical of crustal metamorphism.

Physical and chemical properties: Tolliametile crystallizes in the monoclinic system and tends to appear prismatic in habit. Color ranges from olive-green to bronze, with a metallic to pearly luster and a translucent to opaque appearance. Mohs hardness is reported around 6.5 to 7, and the specific gravity lies roughly between 3.2 and 3.6. The mineral is described as a complex silicate with variable occupancy by iron, manganese, and titanium, reflecting a mixed-cation composition that can influence both color and opacity.

Uses and significance: Because of its rarity, tolliametile is primarily of interest to collectors and researchers. It provides insights into metamorphic mineral formation and crystallography and is occasionally featured in mineralogical reference works as an example of regionally distinctive silicates.

See also: List of minerals named after places; Mineralogy of Tollia region.