Nepheline

Introduction: Nepheline is named after the Greek nephele which means 'cloud', a reference to its appearance when immersed in concentrated acid. It is known to form in rocks that are under-saturated with silica therefore never found with quartz.

Distribution: North of Okahandja, Swartbooisdrif, north-west Kaokoland, the Aris phonolites and in many clusters of carbonatites and alkaline ring complexes outcrop in southern and central Namibia.

Composition: Silicate

Crystal system: Hexagonal

Lustre: Waxy, greasy

Streak: White

Hardness: 5.5-6