Carbonado typical gem diamonds. Lead isotope analyses have been interpreted as documenting crystallization of carbonados about 3 billion years ago. The carbonados are found in younger sedimentary rocks. Mineral grains included within diamonds have been studied extensively for clues to diamond origin. Some typical diamonds contain inclusions of common mantle minerals such as pyrope and forsterite, but such mantle minerals have not been observed in carbonado. In contrast, some carbonados do contain inclusions of minerals characteristic of the Earth's crust: these inclusions do not necessarily establish formation of the diamonds in the crust, however, because while these obvious crystal inclusions occur
Flake tool the blow from the strike it distributed onto the rock in an even fashion, giving the fracture a radial appearance. The production of these lithic tools is only made possible due to their ability to fracture in this way. Examples of such materials include fine-grained materials, such as carbonado, volcanic rocks, obsidian, onyx, and types of glass. These would all be excellent materials for creating flake tools. Flake tools can teach us much about human history. Residue analysis can be done to learn what was processed by the flake tools. Use-wear analysis can give archaeologists an idea of what the