The mountain is an ancient volcanic structure, circular in shape, that rises from flat surrounding plains.

[4] Although geographically located within the Witwatersrand range, the mountain is geologically part of a feature known as the Pilanesberg Alkaline Ring Complex.

[5] It is a vast ring dike of a very ancient extinct volcano that last erupted some 1,200 million years ago.

Different types of syenites, including a number of rare minerals, occur in the crater area.

What we see today is not so much a volcanic crater, but a cross section through the magma pipes that were located at great depth below the mountain's summit.