Andalusite

Introduction: Named after Andalusia in Spain, where this mineral was first discovered. Crystals often elongate, pencil-like and are often red-brown to tan. It is used in the manufacture of high-alumina refractory products and in ceramics production and is an non-corrosive agent. Aluminium is extracted from andalusite and its lightness is used in the aircraft industry.

Distribution: Common in some schists in rocky outcrops to the south-west of Okahandja and in the Kuiseb River valley near the old Gorob Mine.

Composition: Silicae.

Crystal system: Orthorhombic.

Lustre: Vitreous.

Streak: White.

Hardness: 6.5-7.5.