Jambon examined some of the most ancient iron objects ever found, including sheet-iron beads from Gerzeh in Egypt, dated to 3200 B.
C.; an ax from Ugarit on the coast of northern Syria, dated to 1400 B.
His research showed that all the iron in the tested artifacts came from meteorites, and not from terrestrial smelting, he told Live Science in an email.
The findings suggested that iron meteorites were the only source of that metal until the discovery of smelting iron from terrestrial iron ore, probably in Anatolia and the Caucasus around 3,200 years ago, Jambon said.
Most of the iron meteorites that smash into Earth each year are thought to have formed in the metal-heavy cores of planetesimals — small bodies in the protoplanetary disk of debris that orbited the sun during the early stages of the solar system.
As a result, these meteorites contain high levels of nickel or cobalt.
This namespace acts as the version and, by changing this value, you effectively invalidate any other keys that use that namespace: This means that you have to make an additional round-trip per key to retrieve the namespace, but is a good option if you don't have a specific field you could version on (and you don't want to add one).