Fockseile

Fockseile is a fictional mineral species created for worldbuilding and speculative geology. It is described as a sulfide–selenide mineral that forms in hydrothermal environments and is notable for a bright metallic luster and dense habit. The term appears in science fiction and simulation games as a plausible, investigable material.

Composition and structure: In the canonical description, Fockseile forms a solid solution series with selenium-rich sulfide phases. Its approximate empirical formula is (Fe,Ni)(Se,S)2, with cobalt and copper substitutions occasionally reported. Crystallizes in the monoclinic system, producing prismatic, tabular crystals; color steel-gray to black; metallic luster; streak dark gray. Mohs hardness around 4–5; density about 7.0–7.4 g/cm3.

Occurrence and formation: Fockseile is reported in the fictional Fock region's hydrothermal veins, typically in mid-temperature zones (200–400°C) within ultramafic to mafic host rocks. It is often associated with pentlandite, pyrrhotite, and various selenium-bearing minerals. Economic deposits are described as rare and not currently mined in the imagined setting.

Etymology: The name honors a fictional geologist named Dr. Fock and derives from the root Seil meaning rope in the in-world language, alluding to its layered, fibrous habit in some specimens.

Uses and significance: In fiction, Fockseile is considered for advanced semiconductors and thermoelectric applications because of selenium content and potential defect chemistry. In real life, the mineral does not exist; any discussion of uses is speculative within the fictional context.