Meteorites (pieces of rock that fall to Earth from space in the form of spectacular fiery meteors) have been the subject of public admiration, admiration, legend, and religious worship for thousands of years. In recent years, they have become the cosmic Rosetta Stone for scientists investigating the birth of our solar system and the organic life that lives within it. For this reason, meteorites are rightfully classified by many countries as an integral part of the public natural heritage and are in demand by museums and private collectors.

South Africa, where I examine meteors, is one of these countries. At the end of 2021, my colleagues and I learned of an extraordinary opportunity. Gideon Lombaard, a farmer from the Northern Cape province, contacted us because he suspected he had found two meteorite fragments. If true, these would be the first meteorite discoveries in South Africa in more than 40 years.

After carrying out a series of tests, we were able to show that these two fragments were not related to each other, although they were found only one kilometer apart, meaning they probably came from different meteorite events.

In August, the Meteorological Society’s naming committee, which makes decisions about all new meteors, formally accepted our suggestion that the two pieces were different meteors. They approved the names Brierskop and Wolfkop, which we proposed in honor of the monuments near the discovered places.

Mr Lombard’s double discovery brings the number of confirmed meteorites in South Africa to 51; this number is the highest in sub-Saharan Africa. There are 18 confirmed meteorites in Namibia, 12 in Botswana, four in Zimbabwe, and one each in Lesotho and Eswatini. However, compared to the more than 14,000 meteorites found in the Sahara Desert, the number of meteorites found in South Africa is extremely small. Therefore, a concerted national meteorite education and research program could be of great benefit.

What is a meteorite?

The meteorite is a piece of rocky space debris that survived the collision with Earth. Meteors are usually discovered by someone who notices an unusual stone while walking (the so-called find). However, approximately 2% of meteors are classified as “fallers” because they are collected after witnessing meteor fireball events.

The meteorite family includes several different types of rocks. A very small portion of the approximately 72,000 meteorites discovered worldwide to date are actually fragments broken off from the surface of the Moon and Mars by giant collisions. The majority probably originated in the asteroid belt between the orbits of Mars and Jupiter. These are debris from past collisions between some of these asteroids that were launched into orbits and eventually crossed Earth’s path.

Discovery and forensic examination

Finding meteorites is not easy, which makes Mr. Lombard’s double discoveries all the more important. Because meteorites come from space, they often contain iron in metallic or sulfur forms, and they begin to disintegrate rapidly when they come into contact with free oxygen and water.

Therefore, it is not surprising that almost 80% of all meteorites are found in places where the arid climate is conducive to their preservation, namely Antarctica and the Sahara Desert. Meteorites are often covered with a dark thermonuclear crust during their fiery passage through the atmosphere. This makes the white ice of Antarctica and the pale bedrock and sand of the Sahara an ideal background for search engines.

Mr. Lombaard discovered the two meteorites during normal farming activities. The Brierskop meteorite is a 21.19-gram chondrite found on September 18, 2018. Chondrites are the oldest rocks in our solar system, dating back 4.567 billion years. And only after finding the Wolfkop Stone (also a 90.26-gram chondrite) on August 27, 2021, 1 km from the Brierskop site, did he approach it to determine whether it was the meteorite he suspected. If you think you’ve found a meteorite, it’s best to call an expert.

The first photos he sent were quite promising; Then, our main task was to determine whether the two artifacts came from the same waterfall or separate waterfalls. Our analysis, which involved cutting a small piece of each rock and grinding it to create an ultra-thin plate through which microscope light could pass, was able to show that the meteorites had distinct differences.

Brierskop contains less metallic iron and less iron in its parent silicate minerals than Wolfkop. The cartilages (particles in the rock) are much better preserved in Brierscope; This suggests that they experienced less heating of the parent asteroid before the impact that released it. We then used the higher degree of oxidation (rust) of the Wolfkop stone to suggest that its fall occurred before the fall of the Brierskop meteorite.

South Africa’s meteoric legacy

The South African Heritage Act No 25 of 1999 classifies South African meteorites as national heritage sites that cannot be damaged, removed, exported or sold without permission granted by the South African Heritage Agency. The Meteorite Society also requires that meteorites be properly stored and preserved in accredited institutions such as museums and universities for future research. Wolfkop and Brierskop are currently held at the University of the Witwatersrand in Johannesburg, an accredited repository.

According to estimates, an average of 10 to 50 meteors fall on the Earth’s surface every day. Technologies will help make new discoveries. In recent years, more and more countries have deployed camera networks (such as NASA CAMS) designed to record the trajectories of meteor fireballs; These networks can then be triangulated to determine where they fall. The power of citizen science is also being used in many places to volunteer to search for falling meteorites.

Before the last two discoveries, the Meteoritical Bulletin Database listed 49 meteorites that were satisfactorily proven to be from Southern African sites. Thanks to Mr. Lombard’s double discovery, the number of meteorites in the country has exceeded 50. There is no doubt there is more to discover.