Carbonado in the pores that are common in carbonados, they may have been introduced after carbonado formation. Inclusions of other minerals, rare or nearly absent in the Earth's crust, are found at least partly incorporated in diamond, not just in pores: among such other minerals are those with compositions of Si, SiC, and Fe‑Ni. No distinctive high-pressure minerals, including the hexagonal carbon polymorph, lonsdaleite, have been found as inclusions in carbonados, although such inclusions might be expected if carbonados formed by meteorite impact. Isotope studies have yielded further clues to carbonado origin. The carbon isotope value is very low (little carbon‑13
Carbonado, Washington settled during an economic boom in the region. The boom was brought on by raw material demands in nearby growing towns such as Seattle and Tacoma. Starting with the town of Burnett and moving on through Wilkeson, Carbonado, Montezuma, Fairfax, and finally Manley Moore, these settlements sprawled up the valley to the very boundary of Mount Rainier National Park. Most of these towns were company towns, meaning that they specialized in the harvest of raw materials owned the plot of land that the town was situated on and that the resources were harvested from. Often—and such was the case of