Grumbulloj

Grumbulloj is a rare silicate mineral described in mineralogical literature of the fictional world. It was first documented in 2089 by explorations in the Grumbhil Range. The name derives from the local language, with grumbul meaning shade and loj meaning stone. The mineral is notable for its color variability and faint luminescence under ultraviolet light.

Grumbulloj crystallizes in the monoclinic system and commonly forms short prismatic crystals or microcrystalline masses. It has a Mohs hardness near 6, a vitreous to pearly luster, and a specific gravity around 3.3. Its typical composition centers on calcium and iron silicates, with trace vanadium and titanium that influence color, producing olive-green to gray bodies.

Grumbulloj forms in high-temperature hydrothermal veins within metamorphic rocks and is often found alongside quartz, muscovite, and dolomite. Deposits are generally small and unevenly distributed, requiring careful extraction to minimize processing losses.

In practical terms, grumbulloj has attracted interest as a potential ceramic glaze additive and as a subject of study for UV-induced luminescence. Economic exploitation is limited by rarity, location, and mining costs, but laboratory work continues to clarify its crystal chemistry and photonic properties.

The name is incorporated into local folklore, where veins of grumbulloj are said to hum faintly at dawn. Polished fragments are used in decorative inlays in regional crafts within the fictional culture.