AGATE 35 



The localisation of the agate industry in the neighbourhood of Oberstein and Idar, 

 at a very early date certainly more than 400 years ago may be traced to the 

 plentiful occurrence of agates in the surrounding hills, especially in the hill called the 

 Galgenberg or Steinkaulenberg. These hills consist of a melaphyre, more or less 

 amygdaloidal, which has burst through the sandstones of the Saarbriick coal-field. 

 Adits were formerly driven into the hill-side, and the agate-bearing rocks were 

 systematically quarried. The workings in these quarries have for several years past been 

 almost, if not entirely, abandoned, chiefly through the large importations constantly 

 being received from South America. 



In 1827 some Idar polishers who had emigrated to Uruguay accidentally discovered 

 some fine agates, used at that time as paving-stones. Large quantities of the amygda- 

 loidal nodules were easily collected, as loose pebbles, from the bed of the River 

 Taquarie, and were despatched to Oberstein by way of Hamburg. The South American 

 agates are evidently derived from decomposed melaphyre rocks, for although never 

 found actually embedded in the matrix, portions of the mother-stone are occasionally 

 seen adhering to the pebbles. As the agate-nodules are obtained without the expense 

 of quarrying, the cost is confined to that of collecting them from the surface of the 

 ground, or separating them from the superficial detritus. The stones are brought 

 down to the coast on mules, or in waggons drawn by oxen, and are received at Porto 

 Alegre, or at Salto, whence they are taken to Monte Video and Buenos Ayres, and 

 shipped from these ports to Europe. Formerly they left the country free of duty, 

 and were brought over as ballast, but an export duty has now to be paid, amounting 

 in Uruguay to six per cent, of their value, and in Brazil to ten per cent. Arrived at 

 Hamburg, Antwerp, or Havre, the agates are conveyed by rail to Oberstein the 

 rough stones travelling in open trucks, while the choicer carnelians are packed in 

 cases. The total cost of transport by sea and land amounts to from 3s. to 6s. per 

 cwt. Large parcels of the agates are displayed in the courtyards of the inns, and 

 after due advertisement are sold by public auction. Prior to the sale the polishers 

 inspect the lots, and break off samples of the stones, which are taken home and tested 

 as to their power of taking colour by methods to be presently described. From forty 

 to fifty auctions take place annually, and though the prices of the stones vary greatly 

 according to their quality, it may be said that ordinary agates may v be bought on an 

 average for about 15s. per cwt. In 1867, the auction sales for the year realised a 

 gross sum of nearly 16,000^. 



The agates are first roughly dressed with chisel and hammer. From the texture of 

 the stone the experienced workman is able to judge in what directions the stone will 

 most readily split, and hence by a few skilfully-directed blows he manages to trim 

 the agate rudely into the shape which it is intended to assume. The more valuable 

 stones are, however, sawn into shape with emery and water. The grinding is effected 

 on large red grindstones, mounted on a horizontal axis, and rotating in a vertical 

 plane. Each axle carries from three to five stones, and communicates on the outside 

 with a water-wheel. These wheels vary from 10 to 18 feet in diameter, and are 

 usually undershot. Most of the mills are situated on the Idar, a stream which rises 

 in one of the highest parts of the Hochwald. At the village of Idar it is about 1,012 

 feet above the sea-level, and at Oberstein, whore it debouches into the Nahe, it is 905 

 feet high. It is in the Idar valley, between these two villages, that most of the 

 agate-mills are situated. In consequence of the want of water during a dry season, 

 the mills often stand idle, and hence in a few of the larger works steam-power has of 

 late years been introduced. The grindstones, to which the water-wheel or steam- 

 engine gives motion, are made of new red sandstone, quarried at the Kaiserslautern 

 near Mannheim, and are about 5 feet in diameter and one foot in width. They 

 usually make three revolutions per minute. When the stones have been badly 

 selected, or used too soon after having left the quarry, they have been known to fly 

 to pieces with great violence, and in this way several fatal accidents formerly occurred. 

 The wheels revolve in a well, the horizontal shaft being nearly on a level with the 

 floor, below which the lower half of the wheel is concealed. A small stream of water 

 is introduced by a launder above, and by constantly trickling over the stones keeps 

 them moist. Two workmen are generally employed, side by side, at each stone. The 

 workman lies in an almost horizontal position, resting his chest and stomach on a 

 bare wooden grinding-stool, adapted to the shape of his body, while he presses his 

 feet against a block of wood fastened to the floor : the reaction of this fixed block 

 enables him to apply any object with great force to the moving grindstone. The 

 specimen to be ground is either held directly in the hand or applied to the stone by 

 means of a short piece of soft wood. The form is given to the object by holding it in 

 certain channels cut on the circumference of the stone. During grinding, the friction 

 causes the agate to glow with a beautiful reddish phosphorescent light, visible even 

 in the daytime, and quite distinct from sparks elicited by friction, After having been 



