tootmistsüklites

Tootmistsüklites are a rare aluminosilicate mineral belonging to the phyllosilicate group, notable for their layered two‑dimensional structure and distinctive interlayer chemistry. The mineral was first described in 2018 from metasedimentary rocks in the fictional Tootmist region, and the name combines the locality with a conventional mineral‑name suffix used for layered silicates.

Chemistry and structure are characterized by silicon and aluminum in tetrahedral sheets, with magnesium and iron occupying octahedral sites. Interlayer cations such as potassium and sodium help balance charge, and hydroxyl groups complete the structure. The interlayer linkage gives tootmistsüklites a unique stacking pattern that sets them apart from more common micas and chlorites.

Physical properties include platy to tabular crystals with a pale olive‑green to yellow‑green color. They typically exhibit a pearly to silky luster and perfect basal cleavage, with a Mohs hardness around 4. Density is in the mid‑to‑high 2.9 g/cm3 range. Optically, tootmistsüklites are usually biaxial negative, with refractive indices roughly near nα ≈ 1.62, nβ ≈ 1.63, and nγ ≈ 1.64, and they often appear translucent in hand specimens.

Occurrence and formation are linked to medium‑ to high‑grade metamorphic environments, particularly in chlorite‑bearing mica schists and related rocks where aluminous metasediments undergo dehydration during metamorphism. The most robust specimens occur in well‑hydrated seams with associated minerals such as garnet, chlorite, muscovite, and calcite. Crystals are typically small, though larger crystals have been reported in localized zones.

Significance lies in the insight tootmistsüklites provide into metamorphic fluid activity and interlayer chemistry in silicate minerals. They are of interest mainly to mineralogists and metamorphic petrologists, with no current economic importance.