eleutherite

Eleutherite is a rare hypothetical aluminosilicate mineral characterized by an open-framework structure. The name derives from the Greek eleutheros meaning free, in reference to its unblocked channel structure that hosts voids and channels within the crystal lattice.

Discovered in a fictional setting, eleutherite occurs in late-stage pegmatites and high-temperature metamorphic complexes, often forming as slender prismatic to tabular crystals up to 2 cm. The type locality is the Hope Quarry on Eleuthera Island, with type material stored at the National Mineral Archive.

Crystallography and composition: Eleutherite crystallizes in the orthorhombic system with space group Pnma. It is an aluminosilicate with a framework built from aluminum tetrahedra linked by silicon tetrahedra. The mineral contains alkali metals (primarily sodium and potassium) with iron in mixed valence states, and trace lithium and rare-earth elements.

Physical properties: It has a vitreous luster, is transparent to translucent, and typically ranges from colorless to pale yellow or pale green. Hardness is 6.5–7 on the Mohs scale; specific gravity about 3.3–3.6. Cleavage is poor to indistinct; fracture is conchoidal to uneven. Optical properties include weak pleochroism and relief consistent with an orthorhombic mineral.

Occurrence and significance: Eleutherite is studied for its open-framework chemistry and potential porous material applications, including ion exchange and solid-state ion conduction, though it is not currently mined on a commercial scale. Safety follows standard mineral-handling guidelines.