Lead and zinc ores of Scotland Area IV. Caithness and Orkney.

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From: Wilson, G.V. with contibutions by J.S. Flett. The lead, zinc, copper and nickel ores of Scotland. Special Reports on the Mineral Resources of Great Britain Vol. XVII: Edinburgh : HMSO, 1921.
Figure 15. Map of Caithness and Orkney.

Caithness. Details of the mines and veins[edit]

It is probable that veins carrying small quantities of galena are by no means uncommon in the calcareous flagstones which are the commonest rocks of the north and east of Caithness. Heddle, however, records galena from only one locality in that country— Gieuisg Geo in a calcite vein in sandstone flag, with blende, marcasite, calcite and asphalt."[1] Dr. Crampton,[2] in the Geological Survey Memoir on Caithness, reports that " Most of the crushes and joints in the flagstones are sealed by calcite, but locally barytes occurs, and sometimes small quantities of galena, copper pyrites and fluorspar." " Galena . . . occurs in small quantities in company with copper pyrites at North Head, Wick, at Staxigoe, and a few other places along the coast. It has never been found in sufficient quantity to repay working. A richer vein of galena has been reported from Spital, January 1912."

The vein at North Head, Wick, above mentioned, has attracted a good deal of attention owing to its proximity to the principal town of Caithness and the excellent exposure of it in the rocky beach. It has long been known to contain galena and copper pyrites, and samples have been taken from it on more than one occasion and have been assayed. Such trials as have been made in this vein amount only to the removal of a few tons of rock by blasting; there is no record of actual mining operations and no evidence of shafts or adits having been driven.

The position of this vein is shown on the colour-printed Geological map, Sheet 116 (on the scale of one inch to one mile), published in 1914. The vein is very well exposed both in the low cliff and in the rocky beach, and its outcrop can be followed for about a hundred yards. The country-rock is grey, argillaceous flagstone dipping at rather low angles to the north-west. The vein consists of a belt of ciushed flag, up to 15 ft. in width, cemented by calcite and barytes. Here and there galena can be seen in it, but never in promising quantity, and, unless the outcrop has been stripped by collectors, the amount of lead in the vein is probably small. Specks of copper pyrites are seldom visible; the barytes is not good enough or in sufficient quantity to be worth working. Better samples than any now in sight were obtained by blasting at the foot of the cliff about the year 1913, but no mining operations were then attempted.

Achanarras[edit]

Maps: One-inch Ordnance and Geological, Sheet 116; six-inch, Caithness 1'7 S.E.

Situated on the farm of Achanarras, 21 miles S.S.E. of Halkirk Station, and a quarter of a mile south-west of Achanarras Farm.

This vein, as noted by Dr. Crampton, began to attract notice in 1912. Shortly afterwards work was started on it. The mine was visited by Mr. G. V. Wilson[3] in 1915. At that time the workings were mainly on the surface of the vein. He reported that the vein has a north-west course and is nearly vertical; its width is about 5 ft., of which 1 ft. consists of dirty white barytes, and 1 ft. 6 in. of broken stuff with galena; the remainder is made up of crushed country-rocks, which are reddish-grey, drab and bluish Caithness flagstones.

Mining operations were continued on a small scale for several years. A shaft was sunk and drives were made on the vein; galena was the only mineral sought for, and the product of the mine was carted to Georgemas Junction, where it was put on rail. In August 1919 the mine was visited again, and it was found that operations had ceased; the shaft was full of water, but most of the gear remained and seemed in good order. From the heaps of ore lying around the shaft it was ascertained that galena occurred mostly in the form of lumps or crystalline nodules embedded in barytes, calcite and rusty iron oxides.

In the List of Mines, published in the Home Office Reports, this mine appears as active in the years 1917 and 1918 under the ownership of the Toftingall Lead Syndicate; seven or eight men were employed at it.

Orkney. Details of the mines and veins[edit]

The Orkney Islands consist almost entirely of old Red Sandstone rocks, with the exception of a small area of granite and gneiss in the neighbourhood of Stromness. Veins of calcite and barytes containing small quantities of galena are quite common, and have been worked on a small scale at several periods during the last four hundred years; no mines, however, have been producing lead in this county during the last century.

Professor Heddle[4] gives the following localities for galena in Orkney:—Rousay, 1 mile east of Scabra Head; north-west slopes of the Ward Hill, Hoy, at Selwick; Mainland, 1 mile west of the Ness; Fara; Graemsay. To these we may add the following: South Ronaldshay, in several places; Walliwall Quarry, near Kirkwall; Sanday, near Northhill. Lead ore has been reported also to occur at Yeskenaby, on the west coast of the Mainland; in the parish of St. Andrews; near Huip, Stronsay[5] and in Shapinsay; and though these reports require confirmation, there is no doubt that thin veins containing galena are by no means rare in the blue-grey calcareous flagstones which form the greater part of the islands.

Mining for lead in Orkney has been carried on at three or four places, viz., South Ronaldshay, Hoy, Graemsay and Stromness, but all the mines have long since been abandoned, and very few records remain to show at what period they were active and on what scale they were worked. In a description of the islands, in Latin, by Jo. Ben (supposed to have been John Bellenden, Archdeacon of Moray and Canon of Ross), and dated 1529, it is stated that lead ore had been mined in the island of Hoy. There is in the Advocates' Library, Edinburgh, a manuscript containing a " Short Relation of the Most Considerable Things in Orkney," by Matthew Mackaile, apothecary at Aberdeen, in which it is stated that there are old lead mines in Graemsay and Deerness. This account seems to have been written about the year 1680[6] " The (Old) Statistical Account[7] states that the lead mines of Stromness were being worked in the year 1755, but were shut down a few years later. The South Ronaldshay Mine probably belongs to the same period. When Professor Jameson[8] visited the islands in 1799 he did not find any lead mines in operation, and, although trials have been made, no lead-mining has been carried on in Orkney since that date.

Stromness Lead Mine (Abandoned)[edit]

Maps: One-inch Ordnance, Sheet 119; six-inch, Orkney 106.

This mine is situated on the north shore of Hoy Sound, near the old churchyard, about a mile west of Stromness. An old adit is visible, emerging at the base of a low cliff of flagstone; it runs in a northwestern direction, and is still open and accessible. This adit has evidently been driven above the level of high tides, in order to provide drainage for the workings; it can be followed for about 40 yds. in a nearly straight course, and then joins an old working which has a north-east and south-west direction. These workings are full of water and cannot now be inspected.

On the grassy bank above the junction of adit and workings there are the remains of a shaft filled with rubbish. The foundations of the mine houses can also be traced, though all the buildings have been removed; near them there has been a dressing floor, where numerous specimens of lead ore and gangue can still be obtained. The works have evidently been on a very small scale, and it is evident that the mine cannot have been long active. No dumps are visible, and apparently all the waste was thrown on the beach and washed away by the sea.

Specimens gathered on the old dressing floor show that the galena was rather coarsely crystalline, and was scattered through a matrix or gangue, fine-grained, brown or grey in colour, and consisting mainly of barytes, with some calcite and strontianite. The mineral "stromnite," supposed to occur in this matrix, has been proved to be a mixture of strontianite and barytes. A little brown zinc-blende is present in some of the specimens; in small crystals intimately mixed with the galena. There are also greenish, cupreous stains indicating the presence of malachite and other secondary minerals, probably replacing copper pyrites. Some of the lumps of ore are a foot in diameter and contain 25 to 30 per cent. of galena, but it is not likely that they represent the best material obtained.

In " The (Old) Statistical Account," Dr. Clouston says of this mine: " In 1755 miners from England wrought the lead mines, and sent away a considerable quantity of the ore; but either the ore was not rich enough to repay the expenses, or the vein was small and soon exhausted, or the work was unskilfully carried on, and too expensively managed; for one or other of these reasons it was abandoned. A few years afterwards the attempt was again made to open the lead mines in another part of this parish, which also failed."

From the evidence gathered at the mine it seems likely that the ore was exported; no lead slags have been observed, and there is nothing to indicate that the ore was smelted on the spot.

It is believed that the other lead mine referred to by Dr. Clouston was on the shore, near Clestrain.

South Ronaldshay Mine (Abandoned)[edit]

Maps: One-inch Ordnance, Sheet 117; six-inch, Orkney 124.

This mine is on the east coast of the island, on the shore of Manse Bay, about 700 yds. north of the manse.

The only traces of this old mine now visible are the shaft, filled with rubbish, on the top of the cliff, and an adit emerging above highwater-mark, at the base of the cliff. Any buildings that were there have been removed. The shaft is within a few yards of the edge of the cliff; no spoil heaps can be seen, but the waste was probably thrown on the shore and has been washed away by the sea.

The lead vein which was worked lies in a fault which is a strongly marked feature of the geology of the island, and can be followed across it to Sandwick Bay on the west coast, a distance of 4 miles. This fault has a north-east direction, with down-throw to the north-west, bringing grey-blue flagstones against the yellow sandstones of the John o' Groats series. The fault is attended by marked brecciation, and seems to cut across Grimness promontory; a mass of crushed flagstone occupies the fault-plane, and runs along the beach,[9] where it can be followed for several hundred yards. In the dark breccia the lead vein occurs, but hardly any galena is visible in the fault-rock.

We have not been able to ascertain exactly when the mine was worked, but it was probably in the latter half of the eighteenth century. In 1774 Low visited South Ronaldshay, and states in his diary that on his way from Grimness to the manse he saw several deep holes " which I was informed were sunk in search of lead ore, but though this was found in small quantities here, and at Sandhill in the same island, it was found that it could not bear the charge of working, and therefore dropped."[10]

Along the fault a trap-dyke (camptonite) has been intruded; it is practically vertical, and is well exposed in the face of the cliff. This dyke is 3 ft. 9 in. thick, and is later than all the movement along the fault-plane; its relations to the lead vein could not be established, but it seems likely that the vein is later than the dyke. The geological age of the trap-dykes of Orkney is not definitely known, some geologists holding that they tare late-Carboniferous or Permian, while others think them probably Tertiary.

It is well known that deposits of lead ore occur along the line of this fault from Manse Bay to Sandwick Bay; we have seen specimens of galena from the south side of the loch on Vensilly Hill, near the schoolhouse, and the ,ground was recently prospected with a view to mining operations. When Professor Jameson was in Orkney, in 1799,[11] he was told by Mr. Watson, the minister of South Ronaldshay, "that the sandstone, in different parts of the island, has been dug, in the expectation of finding good veins of lead ore (galena), but always without success."

Selwick, Hoy.[edit]

The existence of lead veins in by was known before 1529 (see p. 116), and there is reason to believe that mining has been tried, but on what scale and with what result is not now ascertainable. Probably the mine was at Selwick, on the south shore of Hoy Sound. Professor Heddle[12] records the occurrence of galena there which was said to carry 46 oz. of silver per ton; according to his statements there is little indication of a payable deposit at that locality. Low[13] visited Selwick in 1774 and saw the remains of the old mines.

Other occurrences of galena in Orkney[edit]

Graemsay[edit]

It seems well established that galena occurs in Graemsay, but we have not been able to obtain particulars of the exact locality and nature of the vein. Professor Heddle (loc. cit.) mentions the galena of Graemsay; according to Mackaile[14] there were lead mines in this island, which had been closed down early in the seventeenth century.

Rousay[edit]

The lead mines, 1 mile north-east of Scabra, Head, were known to Professor Heddle, who states that they yielded also azurite, malachite and barytes. About the year 1820 an attempt was made to work them, and we have been informed by a former proprietor of the island that a party of miners was taken from Wales and spent several weeks in the search for profitable veins of ore, but without success. It is stated that on assay the lead ore proved to contain 70 oz. of silver per ton.

Sanday[edit]

A vein of galena was discovered about forty years ago on the farm of Northhill, in Sanday, and was opened up by the proprietor.

Samples were taken and assayed, but no further work was done. The vein occurs in the grey flagstones which are characteristic of the island and traces of the excavation can still be seen; small lumps of galena are scattered about the surface of the fields. Apparently the result of the trials did not encourage operations on a larger scale.

Stronsay[edit]

In "The (Old) Statistical Account" (vol. xv., p. 417, 1815) it is stated that a vein of lead was discovered many years ago on the estate of Huip. " By order of the late proprietor, specimens of ore from this vein were sent to be examined by people of skill; but the result seems not to have been of a flattering nature, for no attempts have hitherto been made to work it."

St. Andrews[edit]

Fragments of lead ore are reported to have been found in this parish.[15]

Deerness[edit]

It is very probably that lead ore was mined in this district several hundred years ago. Jo. Ben reports that in 1506 John Stewart found a gold mine in this parish. A local tradition exists that the lead mine was on. the north coast of Deerness, near the Covenanters' Monument.

Shapinsay[edit]

A manuscript map by George Low, reproduced in his " Tour through Orkney and Shetland," and dated 1774, notes the presence of lead ore in two places on the south side of Shapinsay. Low was a competent observer, and there can be no doubt of his accuracy.

Kirkwall[edit]

At Walliwall Quarry, about a mile west of Kirkwall, small quantities of galena are frequently obtained from veins traversing the grey flagstones which are much used as building stone in the district.

Yeskenaby[edit]

On the west coast of the Mainland, north-west of Stromness, Professor Jameson observed[16] veins of barytes traversing the sandstone; and, intermixed with this barytes, there was calcareous spar, iron pyrites and galena."

Fara[edit]

Professor Heddle[17] reports the occurrence of crystals of galena in Fara, on the authority of Mr. Currie.

References[edit]

  1. M. F. Heddle, Mineralogy of Scotland, 1901, vol. i., p. 17.
  2. C. B. Crampton, The Geology of Caithness, Mem. Geol. Sum, 1914, p. 171.
  3. Special Reports on the Mineral Resources of Great Britain, vol. ii., Barytes and Witherite Mem. Geol. Surv., 2nd edit., 1916, p. 88
  4. Special Reports on the Mineral Resources of Great Britain, vol. ii., Barytes and Witherite Mem. Geol. Surv., 2nd edit., 1916, p. 88
  5. The (Old) Statistical Account of Scotland, vol. xv., 1795, p. 417.
  6. G. Barry, History of the Orkney Islands, 1805, p. 446. The (Old) Statistical Account of Scotland, vol. xv., 1795, p. 453.
  7. The (Old) Statistical Account of Scotland, vol. xvi., 1795, p. 456.
  8. R. Jameson, Mineralogy of the Scottish Isles, vol. ii., 1800, pp. 225-241.
  9. J. S. Flett, The Old Red Sandstone of the Orkneys, Trans. Roy. Soc. Edin., vol. xxxix., 1898, pp 383-424.
  10. G. Low, A Tour through Orkney and Shetland in 1774, 1879, p. 23.
  11. R. Jameson, Mineralogy of the Scottish Isles, vol. ii., 1800, p. 228.
  12. R. Jameson, Mineralogy of the Scottish Isles, vol. ii., 1800, pp. 17 and 18.
  13. R. Jameson, Mineralogy of the Scottish Isles, vol. ii., 1800, p. 4.
  14. G. Barry, History of the Orkney Islands, 1805, p. 453.
  15. The (Old) Statistical Account, vol. xx., p. 261. t Op. cit., p. 232.
  16. The (Old) Statistical Account, vol. xx., p. 232.
  17. M. F. Heddle, Mineralogy of Scotland, vol. i., p. 17, 1901.