These metamorphic rocks are garnet gneiss. The garnet fragments are the round dark brown mineral in the rocks. The rocks measure around 12 cm x 10 cm x 6 cm in size or less. Number of objects in this ...

Geologist Michael Ackerson holds a sample from Canada's Acasta Gneiss formation, home to some of the oldest rocks on the planet. Michael Ackerson We know Earth is old. Scientists estimate that our ...

Under more intense conditions gneiss was metamorphosed into amphibolite. Gneiss and amphibolite contain dark layers or crystals of hornblende, a mineral that’s calcium-iron-magnesium-potassium rich.

Oldest North Cascades bedrock, a 400-million-year-old tale from European origins.

Michigan's Watersmeet gneiss is now estimated to be the oldest rock in the country at more than 3.6 billion years old, researchers Carol D. Frost, Paul A. Mueller, Marion E. Bickford and Robert J ...

Morton gneiss (pronounced “nice”), named for the town in Renville County where it has been quarried, is one of the oldest stones on the planet: about 3.5 billion years old.