The Pienaars Pothole Diamond Mine near Lichtenburg is producing these intensively yellow, orange and red coloured carnelians. The reason for the mining operations (in a depth down to 40 meters below surface) is alluvial diamond-bearing gravel.
The colorization of the carnelian is secondary - after the formation of the agate-nodule iron-bearing liquids are soaked into the porous chalcedony. Carnelians which are showing color-concentration in the outer rim are demonstrating this process very nicely. The Lichtenburg carnelians are reaching a size up to 2 inches, are heavily edge-smoothened and unfortunaly most times only broken sections of complete nodules.”Water-level-pattern” is shown by most of the carnelians from this location.
Similar carnelians are occuring in other regions too ( see “Madagaskar Carnelians”.
More informations about this material and other southafrican gemstones are offered at the homepage of afrigemtec