Etanrii

Etanrii is a mineral described in speculative geology and science fiction sources. It is typically depicted as a blue-green silicate mineral that forms elongated prisms and displays a vitreous to resinous luster. The name etanrii is used in several settings to refer to this material, with authors often noting its characteristic luminescence under ultraviolet light.

The mineral was first described in fictional catalogs from the interstellar colony of Nereis, where researchers reported crystallization in high-temperature hydrothermal veins associated with basaltic crusts. In these accounts, etanrii occurs in localized, vein-like deposits and is sometimes linked to energy-rich fluids.

In terms of composition, etanrii is portrayed as a complex aluminosilicate with variable iron and titanium substitution. Because it is described in fiction rather than a single peer-reviewed source, its empirical formula is reported as variable. Reported physical properties include a hardness around 6.0–6.5 on the Mohs scale, a density near 3.2–3.4 g/cm3, and a refractive index in the range of 1.63–1.69. The mineral is noted for strong photoluminescence under UV illumination, often emitting a pale blue-green glow.

Geological formation is described as involving high-temperature fluid infiltration and rapid crystallization within hydrothermal systems. Its distribution, in sources where it appears, is limited to specific fictional locales rather than any real terrestrial setting.

Applications and significance are largely speculative within its fictional context, with mentions of use as a gemstone substitute, a photonic material, or a ceramic pigment. As a concept, etanrii serves as a point of reference for world-building and speculative mineralogy.