These metamorphic conditions produced rocks with crystals of graphite trapped inside them. On the other hand, amorphous graphite formed when the dead cyanobacteria formed coal deposits ...

Geologists have long struggled to understand massive time gaps in Earth’s rock record, where millions—sometimes billions—of ...

Researchers revisited the isotopic signatures in these rocks. Their findings show that graphite may come from ... suggests that it was formed from metamorphic fluids (at temperatures of over ...