The Hoba meteorite, short for Hoba West, is a meteorite that lies on the farm of the same name, not far from Grootfontein, in the Otjozondjupa Region of Namibia. It has been uncovered but, because of its large mass, has never been moved from where it fell.
The main mass is estimated at more than 60 tonnes. It is the largest known intact meteorite (as a single piece) and about twice as massive as the largest fragment of either the Cape York meteorite's 31-tonne Ahnighito kept in Manhattan or the Campo del Cielo's 31-tonne Gancedo in Argentina. It is also the most massive naturally occurring piece of iron (actually ferronickel) known on Earth's surface.
Hoba is a tabloid body of metal, measuring 2.7×2.7×0.9 m. In 1920 its mass was estimated at 66 tonnes. Erosion, scientific sampling and vandalism reduced its bulk over the years. The remaining mass is estimated at just over 60 tonnes. The meteorite is composed of about 84% iron and 16% nickel, with traces of cobalt. It is classified as an ataxite iron meteorite belonging to the nickel-rich chemical class IVB. A crust of iron hydroxides is locally present on the surface due to weathering oxidation.
The Hoba meteorite impact is thought to have occurred more recently than 80,000 years ago. It is inferred that the Earth's atmosphere slowed the object in such a way that it impacted the surface at terminal velocity, thereby remaining intact and causing little excavation (expulsion of earth). Assuming a drag coefficient of about 1.3, the meteor appears to have slowed to about 320 m/s from an entry speed to the atmosphere typically in excess of 10 km/s. The meteorite is unusual in that it is flat on both major surfaces.
According to wikipedia