BUILDING STONE. 617 
cally developed at and about Springfield. These beds are of particular 
value, as they possess a greater thickness than any one of the under- 
lying formations in the county, and cover a much wider area. In the 
same quarries building stones of excellent quality are combined with 
material that is converted into peculiarly excellent lime. The accom- 
panying section of the rocks at Springfield indicates the relationship of 
the beds. | 
The underlying shale occupies the position of the limestone which 
is quarried so extensively at Dayton and at Piqua. The overlying beds 
of building stone have given the name to the so-called Springfield 
division of the Niagara, and the less compact layers of the overlying so- 
called Guelph formation are broken up and burned. 
The Springfield building stone is a carbonate of lime and magnesia, 
containing only small percentages of silica and alumina. Its usual color 
is a light drab, although blue and yellow courses occur. The lght- 
colored stone sometimes is defaced by faint reddish stveaks which are 
caused by the presence of iron oxide, and which render the stone unfit 
for some of the finer uses. The thickness of this deposit of building 
stone is not more than 20 feet, and is usually less. The lowest courses 
are blue in color, and although massive in appearance, they sometimes 
prove treacherous as building stones, for they are liable to lose their 
dressing surfaces, while their seams widen and they undergo a slow dis- 
integration. The walls of the jail in Springfield furnish an illustration 
of these characteristics. The drab courses are almost all of durable build- 
ing stone, and furnish an invaluable supply of building material for 
Springfield and the adjacent country. 
The difference between the blue and the yellow courses in most of 
the limestones of Ohio appears to depend upon whether the iron exists as 
pyrites or as oxide of iron. The pyrites existing in a fine state of sub- 
division appears black even under the microscope, and the blue color of 
the stones apparently disappears with the oxidation of the pyrites. This 
furnishes an illustration of the circumstance that stones are often im- 
proved by decompositions which take place inside the beds, for if their 
value is not thereby destroyed there is much less danger of a disintegra- 
tion by a decomposition of the quarried stones. 
, From quarries within 13 miles west of Springfield the material for 
the culverts in the state road were obtained, and the material for the 
bridge at Marysville and for the Masonic hall at Urbana. These quar- 
