WHERE TO HUNT MINERALS. 



Since the greater part of the region under consideration 

 is covered with a layer of finely decomposed mineral matter, 

 commingled with organic matter, the underlying rock and soil 

 is completely hidden. If this cover were unbroken, not much 

 attention would be given to Cook County mineralogy. Cov- 

 erings of humus or peat do not deter prospectors who have 

 cause to expect the presence of valuable material. Hunters 

 for topazes and amethysts in the Urals remove the thick cover- 

 ing of moss and humus in thousands of places in the hope of 

 a zone of contact between igneous and other rock. Alaskan 

 miners prospect in spite of the tundras. But near Chicago 

 there are no mineral prizes, and were it not for some favorable 

 conditions the study of the subject would not be encouraged. 

 The mountains of rock along the drainage canal represent 

 quite completely the mineral resources of the Niagara lime- 

 stone (see PL II). The valleys of the Chicago River and the 

 Des Plaines, the lake shore, brick yards, quarries, and gravel 

 banks are very favorable for the collection of emigrant min- 

 erals. The Stony Island quarry furnishes sulphides, carbon- 

 ates, and hydrocarbons. No locality is more favorable than the 

 lake shore, however, as a hunting ground, especially in places 

 where the lake is encroaching on the shore, as at the end of 

 what is known as u The Ridge," near the northern boundary of 

 Evanston where new banks are being formed, and fresh mate- 

 rial is being exposed (see PI. III). Some of the minerals are 

 large enough to be collected and distinguished readily. Some 

 are small constituents of various igneous rocks, so minute as 

 to be collected with difficulty. In this case, the miner's pan, 

 the magnet and the lens can be used to advantage. The bank 

 photographed in PI. Ill is about twenty feet high. The lower 

 ten feet is blue clay of a good quality. The minerals buried 

 in it have been well protected from oxidation, and as the lake 

 encroaches upon it these minerals fall out. The man at the 

 left of the photo is using the miner's pan as gold miners do. 

 The other men are armed with hammer and magnet. 



The novice, in quest of minerals is usually surprised by 

 variegated and queerly-formed specimens that resemble noth- 



