Hoba meteorite
The Hoba meteorite, also known as the Hoba West meteorite, is the heaviest meteorite in the world and the largest naturally-occurring mass of iron known to exist on the surface of the earth. The meteorite, named after the Hoba West Farm near Grootfontein, Namibia, where it was discovered in 1920, has not been moved since it landed over 80,000 years ago. The discovery of the Hoba meteorite was a chance find, as it left no crater or other sign of impact; evidently the Earth's atmosphere slowed down the 66-ton iron body enough so that it fell at terminal velocity. At this speed, the meteorite stayed basically intact, and the low-energy impact with the surface caused little excavation. The meteorite is unusual in that it is flat on both major surfaces, possibly causing it to have skipped across the top of the atmosphere in the way a flat stone skips on water.
The Hoba meteorite is a tabloid body of metal, measuring 2.7 by 2.7 metres (8 feet 9 inches) by 0.9 meters (3 feet). Its mass in 1920 was estimated at 66 tons. Erosion, scientific sampling and vandalism took their toll and over the years the meteorite shrank to just over 60 tons. This led the Government of Namibia then (South West Africa) to declare the Hoba meteorite a National Monument in March 1955, in order to forestall further vandalism.
The meteorite is composed of 84% iron and around 16% nickel with some traces of cobalt. There are crusts of iron hydroxides on the surface in parts. In scientific terms, the meteorite is classed as a nickel-rich ataxite.
The Hoba meteorite was discovered by the owner of the Hoba West farm and was identified and described soon after by the scientist J. Brits. His original report (1920) can be seen at the Grootfontein Museum in Namibia. The owner of the land is said to have encountered the giant meteorite while ploughing one of his fields with an ox. During this task, the farmer heard a loud, metallic, scratching sound before his plough came to a dead stop. The farmer uncovered the meteorite soon after.
In 1985, Rossing Uranium Ltd. made resources and funds available to the Namibian Government so that additional protection against vandalism could be provided. The owner of the farm Hoba West donated the meteorite and the site where it lies to the State for "educational" purposes in 1987. Later that year, the Government opened a tourist centre at the site. As a result of these developments, vandalism of the Hoba meteorite has ceased. It is visited by thousands of tourists every year.
Sources
- Universe: The Definitive Visual Dictionary, Robert Dinwiddie, DK Adult Publishing, (2005), pg. 223.