Many researchers believe life was spawned by natural processes in natural materials on Earth, but often assume the minerals that existed then are the same as they are now; a new study challenges that theory.
The researchers made a list of every mineral that could have possibly existed during the Hadean Eon (the first 550 million years of Earth's existence) and found it was only about eight percent of the 5,000 species that can be found today a Carnegie Institution for Science news release reported.
"This is a consequence of the limited ways that minerals might have formed prior to [four] billion years ago," researcher Robert Hazen said. "Most of the 420 minerals of the Hadean Eon formed from magma-molten rock that slowly crystallized at or near Earth's surface-as well as the alteration of those minerals when exposed to hot water."
Many mineral species originate from living organisms, such as in bones and shells, or are byproducts of photosynthesis. There are also minerals that have taken billions of years to form, so they could not have existed during these early years.
"Fortunately for most origin-of-life models, the most commonly invoked minerals were present on early Earth," Hazen said.
The team believes clay minerals (which have been known to undergo complex chemical reactions) were abundant during the Hadean Eon. "Sulfide minerals, including reactive iron and nickel varieties, "were also present during Earth's childhood years.
Many origin models rely on the presence of the minerals borate and molybdate; this new research suggests these substances may not have been available at the time, which would shoot down the theory.
The researchers hope to study how asteroid impacts affected or changed Earth's mineral composition. The impact would have caused fractures in Earth's crust that filled with hot water and elicited chemical reactions. The team would also like to find out how the moon and planets like Mars developed in terms of their chemical makeup.
