Ilmarasit

Ilmarasit is a fictional mineral described in fantasy literature and world-building games. It is typically characterized as a translucent to pearly mineral with an iridescent play of color, ranging from teal to violet, and a vitreous to resinous luster. The mineral is said to form in ultramafic igneous rocks under high-temperature metamorphism and metasomatic events, and its composition is described as variable, often dominated by magnesium- and aluminum-rich silicates with trace nickel or chromium.

Etymology and naming: The name ilmarasit is attributed to a legendary figure associated with weather in northern myths, combined with a mineral suffix -asit. The term is used consistently in regions of the fictional world to denote this particular gemstone.

Occurrence and history: Primary deposits are described in the Nordhavn High, a mountainous region in the lore. Ilmarasit has become a coveted gem in jewelry and in runic inscriptions due to its color-shift and believed energy-storage properties. The earliest written references appear in chronicles from the mid- to late fantasy eras.

Properties and uses: In-universe, ilmarasit displays strong color-change with light direction and quality; measured refractive index is given as approximately 1.72–1.82, and Mohs hardness as 6–7. It ranges from transparent to translucent with a conchoidal fracture. It is used in ornamentation, gemstone jewelry, and as a focus in magical or technological devices within the setting. Some cultures credit it with weather-protective and luck-bringing properties.

Mining and distribution: Ilmarasit is scarce, with primary deposits in secluded mountain belts. Extraction is controlled by guilds or kingdoms, and sustainable mining practices are a developing theme in the lore.