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Unst, Hagdale, Chromate Quarry, Horse Mill

Horse Engine House (19-20th Century)

Site Name Unst, Hagdale, Chromate Quarry, Horse Mill

Classification Horse Engine House (19-20th Century)

Alternative Name(s) Baltasound; Hagdale Chromite Mill

Canmore ID 253125

Site Number HP61SW 31.01

NGR HP 64051 10272

Datum OSGB36 - NGR


Ordnance Survey licence number 100057073. All rights reserved.
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Administrative Areas

  • Council Shetland Islands
  • Parish Unst
  • Former Region Shetland Islands Area
  • Former District Shetland
  • Former County Shetland


Publication Account (1997)

The chromite ore occurs within a thick band of serpentine and is concentrated in the area of Balta Sound and Hagdale. The ore appears to have been exploited from the 1820s onwards, and by 1840 there was a large quarry at Hagdale which was operated until 1862. The mill is thought to have been bupt around 1850 for the purpose of crushing and thus concentrating low-grade ores.

This is a very attractive relic of Shetland's industrial past, with its yellow drystone walling. It has been partially restored, and, although it is now roofless, recesses on the inside of the circular wall suggest that it may have had some form of light roofing. There is a single entrance and slits in the wall to allow daylight.

The mill is sited astride a small burn that rises in a pond to the west of the mill and runs down to the sea at Wick of Hagdale. The water was directed through the mill by means of small openings at ground-level on the west and east sides and stonelined channels across the mill interior. At the centre is a circular stone-kerbed recess containing an ironbound millstone, and another such stone with an iron tyre lies alongside. A paved walkway for the pony or pair of ponies surrounds the central pit. The smallest ponies in Shetland came from Unst and north Yell, and they would have been ideal for the mill.

Research is still in progress on the exact mechanism used here. Similar devices for crushing ore are known elsewhere in Britain, for example in Derbyshire and Devon, where they were set up in the open air. An iron-clad millstone was fixed vertically to a horizontal axle, and the axle was attached to a central pivot. The horse was harnessed to the other end of the axle and walked round in an anti-clockwise circle, and the vertical millstone crushed the ore placed in its path. At Hagdale it seems likely that the vertical millstone was set to run round the perimeter of the central recess, where the running water would carry away the debris and the heavier ore would remain in the recess. The octagonal stone with a large square perforation is likely to have been a weight (see p. 44).

Information from ‘Exploring Scotland’s Heritage: Shetland’, (1997).


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