rustoisia

Rustoisia is a fictional iron oxide mineral described in speculative geology and science fiction. It is typically depicted as an earthy, brick-red material that forms in oxidizing environments and weathered iron formations.

Its name combines 'rust' with the suffix -oisia, signaling its iron-oxide character and fictional status.

Rustoisia was first described by a fictional geologist, Dr. Lia Korden, during a 22nd-century expedition to the Iron Basin, a non-existent mining district.

In the story world, it forms by prolonged weathering of iron-rich rocks under strong oxidizing conditions, often alongside hematite and goethite; it appears as crusts, botryoidal masses, or tabular crystals in hydrothermal veins.

Chemically, rustoisia is portrayed as a hydrated iron oxide with approximate formula Fe2O3·nH2O. It shows brick-red to reddish-brown colors, an earthy to dull luster, Mohs hardness around 5, and a density near 4.8–5.2. It is largely insoluble in water and only weakly magnetic.

In fiction economies, it is used as a pigment and as a ceramic filler; its stability at moderate temperatures makes it attractive for weathering-resistant coatings in imagined technologies.

Handling is described as low risk, though dust can irritate the lungs. Mining and processing in oxidizing zones are depicted as hazardous.

Related minerals in the setting include hematite, goethite, limonite, and jarosite.