How Diamonds Are Made By Nature.
This BBC article shows us in interesting pictorial presentations how diamonds are made naturally within the Earth’s environment. Almost every diamond that has been dated, formed during the Precambrian Eon – the span of time between Earth’s formation about 4,600 million years ago and the start of the Cambrian Period, about 542 million years ago. In contrast, the earliest land plants did not appear on Earth until about 450 million years ago – nearly 100 million years after the formation of virtually all of Earth’s natural diamonds. Geologists believe that the diamonds in all of Earth’s commercial diamond deposits were formed in the mantle and delivered to the surface by deep-source volcanic eruptions. These eruptions produce the kimberlite and lamproite pipes that are sought after by diamond prospectors. Diamonds weathered and eroded from these eruptive deposits are now contained in the sedimentary deposits of streams and coastlines. The formation of natural diamonds requires very high temperatures and pressures. These conditions occur in limited zones of Earth’s mantle about 90 miles (150 kilometers) below the surface where temperatures are at least 2000 degrees Fahrenheit (1050 degrees Celsius). This critical temperature-pressure environment for diamond formation and stability is not present globally. Instead it is thought to be present primarily in the mantle beneath the stable interiors of continental plates. Tiny diamonds have also been found in rocks that are thought to have been sub-ducted deep into the mantle by plate tectonic processes – then returned to the surface.
Read Article Here: