Related: What's the difference between a rock and a mineral? Rocks located in the Acasta Gneiss Complex in northern Canada have been dated to 4 billion years ago, making them the oldest ...

Pasofino says several holes contain broad intervals of pyroxene gneiss with sulphide minerals – this is encouraging as gold at the nearby Tuzon and Dugbe F deposits is hosted by a similar lithology.

Lewisian gneiss is metamorphic rock, which means it was formed by being heated up and put under great pressure, deep within Earth’s crust. This process causes minerals to crystallise out, resulting in ...