Acasta Gneiss: this polished sphere is a sample from the oldest known rock formation on Earth- rocks from this area are dated as old as 4.03 billion years old based on multiple and mutually consistent radiometric dating techniques. This gneiss is only found in the Northwest Territories of Canada and was collected by Yellowknife resident Mark Brown. Happy Earth Day 2024! ➡️ Follow the link in my profile for info on how to obtain a chunk of the oldest piece of Earth for yourself (and many other sc