I was intrigued by the form of the spheres, grooves around the middle and the fact that they are as hard as steel, while the material (pyrophyllite) in which they are found, is as soft as limestone with a count of only 3 on the Moh scale.
As you probably know, pyrophyllite (Al2 Si4 O10 (OH)2) is a secondary mineral and the deposits were formed by a process of sedimentation. On Gestoptefontein volcanic activity was responsible for the forming of outcrops varying in height from about 10 to 100 meters. The smooth and relatively soft surface on the slopes were ideal for the prehistoric dwellers (San) to make their engravings of animal and abstract designs.
On Gestoptefontein these outcrops were "swan" into huge pieces by means of twisted steel cables running zig-zag on pulleys for several kilometers. These blocks were then sawn by the same method into more manageable pieces of about 500 x 500 mm. Occasionally the "sawing cable" got stuck on one of the metal spheres embedded in the pyrophyllite.
They vary in size from " 30 – 50 mm in diameter and have perfectly concentric grooves round the center as if they were molded. Inside the hard "shell" some have a spongy substance, while in others it resembles charcoal.
When only partly embedded so that they can be seen on the surface, they are not all spheres, but some are also oblong in form.
According to Professor Andries Bisschoff of the University of Potchefstroom (retired some years ago) they are limonite concretions. Due to the relative scarcity of the spheres and the almost impossibility for outsiders to obtain samples from the mine, his conclusions have not been verified by other scientists.
It is very strange that the grooves are always and only round the center. Mr. Credo Mutwa, a notorious witch doctor from the city of Soweto was brought to the museum by a TV – team some years ago and he as well as some amateur archaeologists believed the spheres to be from outer space. It is also hard for me to believe their theory. The original sphere exhibited in this museum was stolen by a white sangoma (witch – doctor) - not Mr. Mutwa, for its supposedly magic qualities and was never retrieved.
Inquiries were made from all over the world about this phenomenon. Countries include Canada, Switzerland, Denmark, Germany, England, USA, Norway, France and Botswana. Institutions such as the University of South Florida, Miles Price and Associates, the Society for Physic Advancement (S.A), Kokkolan Kaupunchi (Finland), Esotera (Germany) Geologisches Institut der Universiteit Pleicherwall (Germany), the Department of Philosophy UICC (Chicago), Danfoss (Denmark), Illustreret Videnskab (Coppenhagen), Louisiana Geological Survey, Gale Research Company (Michigan) and Search and Research Institute of Florida also made inquiries.
NASA was written, to confirm or deny this in 2000, and a reply was never received. Mr. Hund's letter was removed from the Klerksdorp Museum page, afterwards, when I checked back some time later, and the page re-designed.
And in Sept. 2012, an interesting coincidence found on MARS, by NASA.
NASA's Mars rover Opportunity, still active after all these years, has just discovered a dense accumulation of puzzling little spheroids in a rock outcrop on the Red Planet.
FULL STORY: http://science.nasa.gov/science-news/science-at-nasa/2012/14sep_mysteryspheres/