A meteorite worth more than a few million or ten million dollars is likely not possible to be found on Earth after impact without a globally catastrophic event, and the particular question of a meteorite of “billions of dollars” therefore is about an impossible hypothetical
For a meteor to be worth at least $1B, it has to have a weight on the order of magnitude of 12,000 tonnes. (see reference below)
A comparable size meteor would be the Chelyabinsk one which had an approximate weight of between 11,000-13,000 tonnes upon entry; however, the heavier the asteroid the greater the explosion it creates upon entry which should probably result in less matter to remain in a condition that allows for its monetization or obtaining in the first place. The Chelyabinsk created an explosion of about 400-500 kilotons or 26-33 times the energy released in the nuclear explosion of the atomic bomb dropped on Hiroshima.
In 1908, during the Tunguska event, a much larger explosion of about 12,000 kilotons was recorded where the meteor had about 9 times the volume (and likely proportionally larger mass) of the Chelyabinsk meteor. According to its Wikipedia article:
“It is classified as an impact event, even though no impact crater has been found; the object is thought to have disintegrated at an altitude of 5 to 10 kilometres (3 to 6 miles) rather than to have hit the surface of the Earth.”
For that much of mass to remain, if possible at all, after the impact, likely, you would need something closer to the asteroid that rendered almost all life in the animal kingdom on Earth extinct 65 million years ago, and in that sense, the question, in its scale, hypothesizes an impossible scenario.
The above is important because negligible probability of an event is the basis of a general legislative practice not to regulate a hypothetical scenario while the judiciary will not take up a case at all merely on a hypothetical in common law jurisdictions while civil law jurisdictions, for constitutional norm control or to similar ends, will not take up a case without at least passed law that a constitutional or supreme court would suspect unconstitutional.
- Considering smaller space objects, a high-value meteorite of approximately
$100,000, and the sixth largest in Michigan apparently was not
disputed on grounds of ownership by the government despite its
publicity which suggest that neither the State of Michigan, nor the
U.S. government or under any international treaty, no international
body like the UN had claim on the rock. In Michigan, it probably
belongs to John Smith. An article on Space.com reads:
“[In early 2018], [a] man who purchased [a] farm in 1988 and obtained [a] meteorite as part of the property brought the space rock to Central Michigan University (CMU) for examination.”
I would assume CMU knew the protocol, and there appears to have been no action taken to confiscate the rock from the man.
Similar cases when finders sold their meteorite are known from other states, like Connecticut states in Australia, provinces in Canada, and other countries like Costa Rica, Indonesia etc.
Based on 1, there appears to be no international law, therefore its probably “free for all”.
Sovereign states have claims on certain areas of the poles, and special international treaties are also applicable. Likely each jurisdiction should be considered separately to answer this question and that is beyond the scope of a single question to answer.
Additional reference for the downvoters:
The highest valued meteorite was sold for €1.7M euros, or about $1.9M with a weight of about 1 metric ton which translates to about $2 per gram despite its rare composition indicating an inversely proportional correlation between rock size and per gram dollar worth — the Indonesian meteorite ca. 2 kg’s was reported to be valued at $850/gram although likely sold for orders of magnitude less. Bottom line, the bigger the rock, the lesser it is worth per gram, and over a size the bigger the meteor, the likelier it is that it will explode and bigger the explosion will be no later than on impact with the surface of Earth, and the bigger the released energy the more mass will melt and evaporate upon and after impact. The higher the expected worth of a meteorite is the logarithmically less likely it is that it is even possible.