tilkus

Tilkus is a fictional mineral featured in speculative geology and worldbuilding. Described as a translucent silicate with an iridescent, color-changing sheen, tilkus appears in various narratives as a material of aesthetic and technical interest. The name is commonly attributed to the fictional geologist Dr. Celia Tilkus, who is said to have documented the mineral in late 19th-century field notebooks.

Physical properties commonly attributed to tilkus in these works include a color range from colorless to pale blue or green, a vitreous luster, and a Mohs hardness around 5.5. Descriptions often note subtle internal banding and a low to moderate thermal conductivity, features that make tilkus attractive for decorative use and speculative optical applications.

Geological occurrence in the fiction typically places tilkus in hydrothermal veins within mafic to intermediate rocks, often in zones of metasomatic alteration. The mineral is frequently described alongside quartz, chlorite, and magnetite, and authors sometimes present laboratory syntheses of tilkus under controlled high-temperature, high-pressure conditions to explore mineral formation.

Uses and cultural reception in the stories vary; tilkus serves as a plot device for jewelry, currency-like tokens, or lightweight optical components in steampunk and dieselpunk settings. As a fictional mineral, tilkus also provides a convenient example of how real-world naming conventions are adapted in imagined scientific systems.