Ferborite hubnerite

Introduction: Ferberite and Hubnerite are two tungstates that form the 'Wolframite Group'. Ferberite is an iron species and hubnerite a manganese species. Minerals form heavy, prismatic crystals that can be brown, red-brown or black in colour. Tungsten has the highest melting point of any crystal (3,410º C). Electric filaments in light bulbs are made of tungsten. Tungsten carbide is used in drill bits, abrasives and in tool apparatus.

Distribution: Krantzberg tungsten mine north-east of the Erongo Mountains and the Brandberg Mountains.

Composition: Tungstate.

Crystal system: Monoclinic.

Lustre: Submetallic to adamantine (ferberite), submetallic to resinous (hubnerite).

Streak: Black to brown-black (ferberite), red-brown to yellow (hubnerite).

Hardness: 4-4.5.