BUILDING AND ORNAMENTAL 8T0NES. 395 



the rock very easily (iiiurricd and obtainable in blocks of almost any 

 required dimensions. The stone is soft and easily worked, takin<;- read- 

 ily a smooth surface, but no polish. It can be turned on a lathe, and is 

 made into balustrades and other forms of ornamental work. It can be 

 carved in bas relief, but is not sufficiently tough for high reliefs that are 

 to be exposed to the weather. To produce smooth surfaces for flagging, 

 etc., the stone is planed by machines somewhat similar to those used in 

 planing iron. The stone from the immediate vicinity of Lemont is said 

 to contain less iron and to tarnish less readily than that a few miles 

 distant at Joliet. 



The stone in the quarry contains much moisture, and during cold 

 weather care has to be taken to avoid injury by freezing until the (|uarry 

 water has evaporated. This causes a considerable annual expense in 

 making: earth protections, except in those few quarries that are so situ- 

 ated that they can be Hooded with water during the winter months. 



The quarries extend for nearly 4 miles below Lemont, where a gap oc- 

 curs, to just below Lockport, from which point a line of closely-adjoining 

 (juarries extend to below Joliet. The finer varieties of the stone do not 

 seem well fitted for heavy masonry in damp situations. Fine clay seams 

 abound, which arc invisible when the stone is first quarried, and which 

 uiuler favorable circumstances do not develop at all, but when exposed 

 to heavy pressure or to alternate moisture and dryness, accomi)anied by 

 frost, they are soon developed, and often render the stone worthless. 

 Even the best varieties of the stone tarnish after a short exposure, es- 

 pecially in cities where soft coal is burned. 



The Joliet quarries extend from a point about a mile below Lockport 

 to the same distance below Joliet. Two distinct varieties of stone occur. 

 That quarried from the lower beds on the riglit bank of the river is 

 as a rule rougher, more coarsely textured, and tarnishes more readily 

 than that from the higher levels. It is now but little used, except for 

 heavy masonry. In the quarries back from the river, on the higher 

 levels, the stone is fine grained, nu)re homogeneous, aiul in this respect 

 fully equal to the Lemont stones. The beds now worked are from 3 to 

 4 feet in thickness, and large l)lo(;ks are obtainable. Most of it seems 

 to weather-stain rather more than that from Lemont. The value of the 

 stoiui quarried at these two places is iirobably fully equal to that of all 

 the other stone quarried in the State.* 



Three large quarries are worked in these same formations at Batavia, 

 but as a rule the stone is coarser and more dillicult to work than those 

 just described. Other quarries occur at Thornton and Blue Island, 

 ('ook County, and other i)arts of the State, as noticed in the catalogue 



* ThcHO beds wore ibrmorly (loscribed an cdiiiposcd oi' light butt' stoue, wliile tbe 

 (loepcr portions of tlio quarries now Inrnish " l)lii('Htone." Tbo fliffcrence results 

 from tbc dififV-niiHio in amount of oxidation of tbo small amonnt of iron disseminated 

 througb tbo whole mass, tbe change having rcsnltiul from atmosidieric influences. 

 The same change must ultimately take place in all the blucstouo which isbroiiglit to 

 the surface. (Geology of Illinois, Vol. iv, p. 220.) 



