Arkohiekka

Arkohiekka is a fictional mineral resource used in science fiction and fantasy world-building. The name combines arko- from arkose with hiekka, the Finnish word for sand, signaling its arkosic, sand-like character.

Geological characteristics: Arkohiekka is described as a coarse to medium-grained arkosic sandstone with elevated feldspar content, typically 50–70% feldspar and 25–40% quartz, plus 5–15% rock fragments and mica. It forms in alluvial or deltaic settings where rapid sedimentation preserves feldspar before complete weathering. The material often exhibits intergranular porosity and a light-brown to tan color, with darker bands where iron oxide inclusions occur.

Physical properties and applications: In the fictional setting, Arkohiekka has a hardness around 6 to 7 on the Mohs scale and a bulk density of about 2.4–2.8 g/cm3. It is valued for its high total alkali feldspar content, making it suitable for refractory ceramics, specialized glass production, and construction aggregates. Its porosity and grain size permit relatively easy processing into graded sands or compacted blocks.

History and naming: The name Arkohiekka is credited to field geologists in the northern arkose basins of the fictional continent of Nordara, with the first formal description in the mid-22nd century in a report by the Nordaran Geological Society.

See also: Arkose, Silica sand, Feldspar, Sedimentary rock.