On a Remote Island, a Lost Part of the World Is Found

Furthermore, Anjouan is dominated by the much larger island of Grande Comore, and has been the scene of repeated uprisings—the most recent in October 2018, when six days of shooting and explosions killed an unknown number of people in the capital city of Mutsamudu before government is no direct route to Anjouan from almost anywhere, and few facilities for visitors. The rock could not have formed on Anjouan, because the basalt that formed the island does not contain any quartz. Through analysis of scattered mineral grains, scientists have long inferred that bits of continental rock do end up in ocean basins, but these get destroyed by volcanism and other forces, and so the evidence consists only of chemical remnants; apart from Anjouan, the rocks themselves have never been documented.

Source: blogs.ei.columbia.edu