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 Life what he needs from his old band – that insinuating hook sense – and uses it to frame an utterly comfortable metaphysical discourse". Alan Clayson describes "What Is Life" as a seemingly "lovey-dovey pop song" that "craftily renewed the simplistic tonic-to-dominant riff cliché", while Simon Leng credits Harrison's "innate ability to write very fine pop-rock songs" and deems the result "as innovative an exercise in rock-soul as The Temptations' 'Cloud Nine'". Among Harrison biographers, only Ian Inglis is less than enthusiastic, acknowledging that Barham's orchestration and the other musicians give the track "undoubted excitement and energy", but lamenting that the