geleneini

Geleneini is a hypothetical mineral species commonly cited in geoscience pedagogy and speculative fiction to illustrate high‑pressure metamorphic processes. In these contexts, geleneini is described as a transparent to pale-colored silicate that crystallizes in the hexagonal system and forms under ultrahigh‑pressure conditions thought to occur in the lower crust and upper mantle.

Origin of the name is attributed in fiction to the 21st‑century geologist Dr. Lidia Gelenein, with the term serving as a neutral placeholder in discussions of mineral stability.

Typical properties attributed in fictional descriptions include a vitreous to pearly luster, hexagonal prismatic crystals, two perfect cleavages, and a hardness near 6 on the Mohs scale. It is described as having a refractive index around 1.66–1.70 and low to moderate birefringence, depending on crystal orientation.

Occurrence and formation are described as taking place in metapelitic or eclogitic rocks subjected to sustained ultrahigh-pressure conditions, often in proximity to minerals such as garnet, sapphirine, and coesite. In theoretical models, geleneini helps illustrate phase transitions between stable silicate polymorphs under mantle‑depth pressures and temperatures.

Laboratory discussions of geleneini involve high‑pressure, high‑temperature synthesis, typically using diamond‑anvil cells or multi‑anvil presses, combined with in situ diffraction and spectroscopic analysis. The mineral is not recognized in real-world geology and is used primarily as a didactic or narrative device.

See also: ultrahigh‑pressure metamorphism, silicate minerals, mineral stability, diamond‑anvil cell experiments.