virrankulun

Virrankulun is a rare vanadium-bearing silicate mineral known for its iridescent luster and distinctive hexagonal crystal habit. It occurs as slender prismatic crystals embedded in hydrothermally altered ultramafic rocks and in veined pockets within the Virrand Basin. The mineral’s appearance ranges from blue-green to iridescent gray, with a metallic to vitreous luster and conchoidal to sub-hexagonal fractures. Chemical analyses show substantial vanadium and titanium, with aluminum substitution creating variable compositions. The idealized formula is variable, but commonly described as (V,Ti)Al2Si3O12 with broad solid-solution along the V–Fe axis.

Virrankulun was first described in 2145 by researchers from the Terra Mineral Institute after specimens were collected in the Virrand Basin, a geologic province on the fictional continent of Asteria. The name combines virra, meaning bright in the local vernacular, with kulun meaning stone.

In the field, virrankulun crystallizes in the hexagonal system, forming slender prismatic crystals up to several centimeters long. Its measured refractive indices and birefringence (nω ≈ 1.72, nε ≈ 1.83; birefringence ≈ 0.11) give it notable optical properties, and its hardness is around 6.5 on the Mohs scale. Specific gravity ranges from 4.0 to 4.6.

Occurrences are centered in the Virrand Basin, where high-temperature hydrothermal activity acted on ultramafic host rocks; secondary pockets have been reported in nearby belts. Associated minerals include chromian spinel, rutile, garnet, and xenotime.

Uses and significance: Virrankulun is primarily of interest to mineral collectors and researchers. Its optical and crystallographic properties make it a potential reference material for metamorphic geobarometry studies, and its rarity limits commercial use in jewelry and ornamentation.