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 song offers "little overall coherence between words and music". In a 2010 poll to find the "10 Best George Harrison Songs", AOL Radio listeners voted "What Is Life" third behind "My Sweet Lord" and "Blow Away". A similar list by Michael Galluci of Ultimate Classic Rock placed it second (behind "My Sweet Lord"), as Galluci wrote of the track having "a giant pop hook as its guide" as well as "the catchiest chorus Harrison ever penned".<ref name="Gallucci/UCR">Michael Gallucci, "Top 10 George Harrison Songs", Ultimate Classic Rock (retrieved 28 March 2014).</ref> In 2009, Matt Melis of Consequence of Sound listed it