Ultima Thule; or, A Summer in Iceland. vol. 2/2

by Sir Richard Francis Burton

Another reason for the impurity of the sulphur is this, that a man, coming to a mine to see how the sulphur is, thrusts his spade into the ground in various places, without first carefully removing the upper earth, whereby the sulphur and the earth become mixed together. If he does not think the sulphur good or abundant enough to be dug out at that time, he leaves the mine thus disturbed; and the rising sulphur is sublimated among the disturbed lumps of earth and sulphur, and the whole becomes a compact mass; it often looks quite pure, but turns out altogether different at the refinery. Thus a single man may in one hour destroy a great many mines that might have been excellent if more carefully handled.

One more cause of the impurity of the sulphur may be found, I think, in the following circumstance. When the peasants come to a good mine they take out all the sulphur that is to be found there, and do not take care how they tread down the loose earth below the sulphur; the down-trodden earth, over which the wind sweeps freely, becomes tough and hard when the heat from below is not strong enough to break through it, and thus keep it porous; thus the mine becomes cold and useless. In other places where the heat is strong enough to force the steam through the trodden earth, there is, however, this disadvantage: Firstly, It takes a longer time for the sulphur to arrive at a state of perfect sublimation than if the earth had remained in its porous condition. Secondly, The fresh sublimation will be impure. When one steps into the loose earth, deep holes, separated by thin ridges, will be formed. When the sulphur is formed in these holes, covering the ridges as well, it is evident that all these ridges must come out with the sulphur at a subsequent digging.

Those that work the mines must therefore be ordered: Firstly, To remove the earth before they dig up any mine, so that nothing shall fall into the sulphur. Secondly, When they remove lumps of earth from the sulphur, they must carry them outside the mine. Thirdly, When they work a mine, they must first remove the uppermost earth; they must not completely empty any mine of its sulphur: they should leave the utmost border standing; then run a trench along the whole length of the mine, then leave a ridge standing, and run another trench, and so on until they have reached the utmost border, which they are to leave standing. Thus the wind will be prevented from having a full sweep of the mine, and thus making it cold. These trenches ought therefore to run across the course of the most frequent winds; these are here, in my opinion, a north-wester and south-easter. After one year the ridges left standing might be taken with the same precaution as mentioned above. The workmen ought therefore to be as much as possible prohibited from stepping into the mines; every digger should take with him a board to stand on while he digs, and this he should move with him as he proceeds. By these means the mines might be saved from being unequally trodden down, and the digger might escape from burning his feet, which he now frequently does, by sinking through the loose and hot soil.

On the east side of the mountain, below the above-mentioned mines, a red “bolus” begins, stretching round the mountain from south to north until it meets with a sandstone mountain; between the mountain and this ridge of “bolus” there is a little sulphur mine, and here the gypseous earth is found below the sulphur as usual. Digging up the real “bolus,” I found it to be very loose and soft; it was full of holes, like the hardened one at Krísuvík, and the holes were filled with lime, very loose and gelatinous, and slimy to the touch. Under the “bolus” the earth was in many places hollow, and one hardly dared to tread there. Very hot vapours arise from the bottom, by which these earths are sublimated, for it is quite as hot here as in the sulphur mines. This is a very interesting circumstance, and well worth observing, that there are two places lying side by side, and presenting such a difference in the stuffs driven up from the bottom by the heat, which is equally great in both places. In one, however, sulphur is sublimated along with a strong acid, and in the other the above said lime is sublimated, and not the least acid is found in it.

Hliðar-námar.

The 15th I went to the so-called Hliðar-námar, which are about eighteen miles distant from the former ones. These are the largest of all the mines, and here too is the greatest heat; the sulphur is consequently sublimated in less time than in any of the others. At present there is a large quantity of sulphur here, but it is all in powder, or in the form of flowers; most of them are found in the mountains, as in the former places; and the sulphur bed is in many places six inches and more in thickness. The reason why the heat drives up greater quantities of sulphur here than in the former places is to be found in the looseness of the soil; it is not only much looser than in the former ones, but in some places even too loose and damp, which both makes the spot difficult to approach in order to dig, and fills the sulphur with earth and impurities, so as to make it useless. The reason why these mines are in such a good condition now is, that the sulphur brought from here to the refinery was not so well received as that which came from the Fremri-námar, or the so-called Theystarreykja-námar nearest to Húsavík. I admit that the sulphur found here is more mixed with earth and acids than in the other places; not, however, in such a degree as to offer any serious difficulties. But as the whole of the sulphur is in the form of flowers, and the earth immediately below it has nearly the same appearance, and cannot therefore be easily distinguished from the sulphur, the peasants do not, therefore, I think, separate the sulphur from the earth with as much care as where it is found in a more solid condition, and where the earth is more easily detected.

The mountain where these mines are situated stretches from north to south, and on the north side it goes a considerable distance beyond the mines. The same kinds of earth are found here as at Krísuvík, except the grey slate, of which there is none here, neither are there any variations in the gypseous earth; and very little of gypsum is to be found, which probably is owing to the higher degree of heat, or it may be because the heat has less interrupted egress, and consequently keeps the earth constantly porous. There is a larger quantity of the vitriolic alum. For the rest, the mountain consists of common sandstone. That even these mines have not been worked carefully is evident from the considerable number of ruined and cold mines.

Below the sulphur mountain on the east side there are three boiling springs; it is evident that the two farthest to the south, and situated close to each other, have been produced by an earthquake, because they are found in a rift in the mountain, and boil with such awful noise, especially the most southern one, that it can be heard 200 yards off, and the ground, which consists of bluish “bolus,” is shaken. Close to these hot springs is a large lava-tract, which spreads to the north to a considerable distance; it also winds round the southern point of the mountain, and crosses the path that leads to Fremri-námar, and spreads almost down to Reykjahlið. The ground is hot everywhere, and the hot vapours rise through the lava, and the whole is therefore continually steaming. About nine miles north of these mines is the mountain Krabla, where excellent mines are said to have been, but when the eruption of 1724 took place, it caused great destruction. One branch of the lava-stream coming from this mountain passed close by the mines on the west side and through the farm of Reykjahlið, the whole of which was destroyed, and at last the current flowed into the lake Mývatn. The lava thus produced was in various places hollow, as if the uppermost crust had been hardened by the air, and the still liquid lava which was under it flowed away. As the outmost crust cooled down by degrees, it contracted, and thus rifts were formed; in some places also it was not strong enough to support its own weight, and fell down. Crawling into these caves, I found a kind of salt which had been sublimated from the earth, and become fixed there. It had a bitter taste, and after being dissolved and dried again it formed square crystals, with a square point. It was easily melted by the blow-pipe.

Theystarreykja Mines.

The 31st of August I came to the Theystarreykja mines, which are about two miles from the refinery. A large quantity of sulphur is said to have been brought from these mines to the refinery, as they were very important ones, but now they are almost all cold, and it is only in a few of them that sufficient heat is found. Therefore, although four years are said to have passed since sulphur was taken herefrom, there are only four or five where it might be taken again. Nevertheless the heat seems in some of the cold mines to be breaking through so far that the vitriolic acid can be sublimated through the ground, as it has in combination with the dissolved lime formed the above-mentioned vitriolic salt. It is therefore to be hoped that many of these ruined mines may recover after a time, yet this is not certain. Here is again a clear instance of how the very best mines may be ruined in a short time by careless treatment. If, therefore, the still remaining mines, either here or in other places, are to be preserved, the peasants must be prevented from digging the sulphur.