BOOK II. 31 



are exposed before his eyes. There are just as great differences in hills as 

 there are in mountains, yet the miner does not dig except in those situated 

 in mountainous districts, and even very rarely in those. It is however very 

 little to be wondered at that the hill in the Island of Lemnos was excavated, 

 for the whole is of a reddish-yellow colour, which furnishes for the inhabit- 

 ants that valuable clay so especially beneficial to mankind 10 . In like 

 manner, other hills are excavated if chalk or other varieties of earth are 

 exposed, but these are not prospected for. 



There are likewise many varieties of valleys and plains. One kind is 

 enclosed on the sides with its outlet and entrance open ; another has either 

 its entrance or its outlet open and the rest of it is closed in ; both of these are 

 properly called valleys. There is a third variety which is surrounded on all 

 sides by mountains, and these are called convalles. Some valleys again, 

 have recesses, and others have none ; one is wide, another narrow ; one 

 is long, another short ; yet another kind is not higher than the neighbouring 

 plain, and others are lower than the surrounding flat country. But the 

 miner does not dig in those surrounded on all sides by mountains, nor in those 

 that are open, unless there be a low plain close at hand, or unless a vein 

 of metal descending from the mountains should extend into the valley. 

 Plains differ from one another, one being situated at low elevation, 

 and others higher, one being level and another with a slight incline. The 

 miner should never excavate the low-lying plain, nor one which is perfectly 

 level, unless it be in some mountain, and rarely should he mine in the other 

 kinds of plains. 



With regard to the conditions of the locality the miner should 

 not contemplate mining without considering whether the place be 

 covered with trees or is bare. If it be a wooded place, he who digs there 

 has this advantage, besides others, that there will be an abundant supply of 

 wood for his underground timbering, his machinery, buildings, smelting, 

 and other necessities. If there is no forest he should not mine there unless 

 there is a river near, by which he can carry down the timber. Yet wherever 

 there is a hope that pure gold or gems may be found, the ground can 

 be turned up, even though there is no forest, because the gems need only 

 to be polished and the gold to be purified. Therefore the inhabitants of 

 hot regions obtain these substances from rough and sandy places, where 

 sometimes there are not even shrubs, much less woods. 



The miner should next consider the locality, as to whether it has a 

 perpetual supply of running water, or whether it is always devoid of water 

 except when a torrent supplied by rains flows down from the summits of the 

 mountains. The place that Nature has provided with a river or stream can 



10 This island in the northern ^Egean Sea has produced this " earth " from before 

 Theophrastus' time (372-287 B.C.) down to the present day. According to Dana (System of 

 Mineralogy 689), it is cimolite, a hydrous silicate of aluminium. The Ancients distinguished 

 two kinds, one sort used as a pigment, and the other for medicinal purposes. This latter 

 was dug with great ceremony at a certain time of the year, moulded into cubes, and stamped 

 with a goat, the symbol of Diana. It thus became known as terra sigillata, and was an 

 article of apothecary commerce down to the last century. It is described by Galen (xn., 12), 

 Dioscorides (v., 63), and Pliny (xxxv., 14), as a remedy for ulcers and snake bites. 



