UNITED NEWS INTERNATIONAL (UNI) — The Earth has given up one of its deepest secrets.

Scientists found a mineral never before seen in nature trapped inside a diamond.

The tiny diamond was found at South Africa’s famous Cullinan mine.

A report published March 7 in the journal Nature said the gemstone contains a mineral called calcium silicate perovskite.

Scientists think perovskite is the fourth most abundant mineral on Earth.

But they’ve never had a chance to study it because it’s thought to exist in Earth’s lower mantle some 700 kilometers below the surface.

Study authors said the only reason this perovskite remained stable as it moved toward the surface is because the diamond formed around it and trapped it in an “unyielding container.”

Researchers say the mineral also supports the theory that oceanic crust below the sea is recycled in the Earth’s lower mantle where the diamond was formed.