by McGill University , EPSL,  May 5, 2017, in ScienceDaily

Conventional theory holds that all of the early Earth’s crustal ingredients were formed by volcanic activity. Now, however, earth scientists have published a theory with a novel twist: some of the chemical components of this material settled onto Earth’s early surface from the steamy atmosphere that prevailed at the time.

More than 90% of Earth’s continental crust is made up of silica-rich minerals, such as feldspar and quartz. But where did this silica-enriched material come from? And could it provide a clue in the search for life on other planets?