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
What Is History? and were instead products of their own places and times, which in turn decided what "facts of the past" they determined into "facts of history". British historian Richard J. Evans said "What Is History?" caused a revolution in British historiography in the 1960s. Australian historian Keith Windschuttle, a critic of Carr, said "What Is History?" is one of the most influential books written about historiography, and that very few historians working in the English language since the 1960s had not read it. What Is History? What Is History? is a study that was written by the English historian E. H.