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
Rock Hawk Rock Hawk Rock Hawk Effigy Mound is an archaeological site in Putnam County, Georgia, United States. () It consists of thousands of pieces of quartzite laid in the shape of a large bird. Although it is most often referred to as a hawk, scholars do not know exactly what type of bird the original builders intended to portray. Only two such effigy mounds have been found east of the Mississippi River. The other, known as Rock Eagle, is also located in Putnam County, approximately thirteen miles to the northwest. () The physical condition of Rock Hawk is far below that