Pentlandite

Pentlandite is an iron nickel sulphide with the chemical formula (Fe,Ni)₉S₈. It is found in nature as bronze-coloured, metallic aggregates in igneous rocks but has also been found in meteorites. It is an important source of the metal nickel and is found at localities around the world.

But when it comes to the name we need to be wary. At first sight, it might be assumed that the mineral is named after the Pentland Hills or the Pentland Firth, two well-known Scottish locations. The area to the south of the city around Loanhead, which included the Pentland Hills, was called Pentland and the name is still found in Old Pentland Cemetery and Farm. This name may come from Middle English pent + land meaning enclosed land.

Pentlandite illustration by Vojta Hýbl.

Moving north, the origin of the name of the Pentland Firth has an altogether different derivation. This name is thought to originate from the Old Norse Petlandsfjörð (Fjord of Pictland) referring to body of water separating the Picts of the mainland from the Vikings who had by then occupied Orkney. The place-name Pentland also occurs in Canada, Australia and the USA.

Bronze-coloured pentlandite from Eas a'Chosain near Inverary, Argyll.

In actual fact, the name derives from a person and not a place. The mineral was named after Joseph Barclay Pentland (1797–1873). Born in Ballybofey, County Donegal, in Ireland, he was educated in Armagh before travelling extensively, studying in Paris with Cuvier then undertaking a survey of the Andes in Bolivia. He was a regular correspondent of Buckland and Darwin. He had noted and worked on material from Sudbury in Canada and the mineral was named after him in recognition of his work.

Joseph Barclay Pentland.

But the story doesn’t end there. The mineral that would eventually be named pentlandite was also found in older material from Craignure Mine in Argyll and from the Espedalen Mine, Gaudal, Norway. These two localities were named as type localities (a type locality is the place where a mineral was first described from).

The surname Pentland is itself thought to have a Scottish origin and the first recorded instances of the name all occur in Scotland, around the Edinburgh area. It may be that the Pentland family from Donegal were part of the so-called “Plantation of Ulster” during the 17th century, when Scottish and English families were settled in the north of Ireland.