Kallioon

Kallioon is a proposed mineral term used in mineralogical discussions to describe a dense, opaque silicate mineral with metallic luster. The name is derived from the Finnish word kallio, meaning rock, reflecting its occurrence in rocky metamorphic terrains.

Physical characteristics: commonly dark gray to black; iridescent when fractured; Mohs hardness estimated around 5–6; specific gravity about 4.8–5.3.

Chemically, kallioon is described as a complex silicate containing iron and magnesium as major constituents, with trace titanium and chromium.

Crystal system and habit: reported as microscopic, elongated crystals with a monoclinic tendency; occurs as inclusions within schist and gneiss.

Occurrence: reported from metamorphic rocks in the Baltic Shield region (Finland, Sweden, Norway), often alongside garnet, biotite, and quartz.

Status: kallioon has not been recognized as a distinct mineral species by the International Mineralogical Association (IMA). Some sources treat it as a rock- or mineral-variation or an identification alias pending further verification.

Uses: mainly of interest to researchers studying metamorphism; potential as a geological indicator.

See also: mineral; metamorphic rock; Baltic Shield.