Focus on finds – haematite
It was something that had long been suspected but we have abundant proof that colour was an important facet of life in Neolithic Orkney.
Various materials were used to produce the different coloured pigments.
Galena, from Warebeth, Stromness, for example, was used to create white, as was bone for pottery. We also know that haematite – the mineral form of iron oxide – was used for the orange/red colours encountered at the Ness.
Haematite is found as solid nodular lumps on the island of Hoy. It has also been found on at least two beaches on the Orkney Mainland.
Used dry, and rubbed against a hard surface, haematite leaves a powdery red mark. Used wet, on the other hand, it produces “a rich, dark-red liquid, which resembles blood” 
A cursory glance through excavation reports from the 19th century onwards reveals that haematite was a common find at Orcadian Neolithic settlements.
In 1867, George Petrie commented on “a small piece of red pigment” which had been “partially rubbed down” at Skara Brae.
He later linked this pigment to haematite as “several pieces of the ore were found in the ruins.” 
Decades later, in the 1920s, Childe found “paint pots” containing pigment at Skara Brae. These, he believed, were for body adornment. The lumps of “metallic-looking material” he also encountered were subsequently identified as haematite – “no doubt . . . the raw material which has been ground down for a red pigment.” 
Despite the early connections between haematite and coloured pigment at Skara Brae, for years it was assumed the highly polished nodules were used for smoothing animal hides.
But as experimental archaeologist Arlene Isbister pointed out in 2000: “A highly burnished nodule of haematite will polish leather, but a similar finish can equally be achieved using a polished pebble.” 
If fact, she added: “[L]eather polishes haematite better than haematite polishes leather.”
Her conclusion? That haematite was, first and foremost, a raw pigment source in the Neolithic.
It wasn’t long after excavation began at the Ness that haematite began appearing.
To date, 19 pieces have been found, five of which are highly polished and show facets and striations from rubbing. Almost half of these came from Structure Ten, which also, perhaps unsurprisingly, was found to contain a pigment production area in its secondary remodelled phase.
That haematite was used to colour the stonework and pottery at the Ness is without question – chemical analysis has confirmed it. There is now little reason to doubt it had the same role at Neolithic sites across Orkney.
-  Jones, R., Towers, R., Card, N. and Odling, N. (2019). Analysis of coloured Grooved Ware sherds from the Ness of Brodgar, Orkney. Journal of Archaeological Science: Reports, 28, p.102014.
-  Clarke, A. (2011) Does Size Matter – Stone Axes from Orkney: their style and deposition. Stone Axe Studies, 3, pp.309-322.
-  Petrie, G. (1867) Notice of Ruins of Ancient Dwellings at Skara, Bay of Skaill, in the Parish of Sandwick, Orkney, recently excavated. In Proceedings of the Society of Antiquaries of Scotland (Vol. 7, pp. 201-219).
-  Childe, V., Paterson, J. and Bryce, T. (1928) Provisional Report on the Excavations at Skara Brae, and on Finds from the 1927 and 1928 Campaigns. With a Report on Bones. In Proceedings of the Society of Antiquaries of Scotland (Vol. 63, pp. 225-280).
-  Isbister, A. (2000) Burnished haematite and pigment production. In Ritchie, A. (ed) Neolithic Orkney in its European Context. pp.191-5.