A BOREHOLE beneath Tyneside has produced another addition to a scientist's collection of some of the most inaccessible rocks on the planet.

Newcastle University geologist Professor Paul Younger has put on display the result of 30 years of painstaking hunting, chipping and polishing to produce slivers of rock no more than 30 microns thick.

The exhibition at the university’s Gallery of Wonder includes samples originating deep underground as a result of volcanic activity.

Prof Younger said: “To the naked eye they’re pretty unremarkable but under the microscope they tell an amazing story in patterns and colours you won’t find anywhere else in nature.

“They are a glimpse into an otherwise unobservable world.”

The rocks date back as much as 2,500 million years and were formed in the deep-seated magma chambers far below active volcanoes.

“In some cases the ancient volcanic activity caused underground cracking of the Earth for hundreds of miles around, the molten rock spreading out to fill the gap,” said Prof Younger.

“Thus the rocks sampled in the Cleveland Hills originated beneath an ancient volcano on the Isle of Mull, some 250 miles away in the Inner Hebrides.

“For geologists, these rocks help us to unravel some fundamental mysteries, concerning the otherwise-unobservable processes that occur deep below our feet.

“There isn’t – and never will be – a way to observe these processes directly, but when we look at these rocks down the microscope, we can reconstruct what must have gone on from the shapes and compositions of the minerals.”