BUILDING AND ORNAMENTAL STONES. 403 



tain a sufficient percentage of magnesia to merit the name maguesian 

 limestone, though scarcely enough to constitute a true dolomite. Many 

 of the rocks belonging to this group are marbles, and have already been 

 described. 



At Greenport, Columbia County, a stratum of Lower Silurian lime- 

 stone upward of GO or 70 feet in thickness is extensively worked for 

 ornamental and building purposes. The quarry proper is said to cover 

 au area of 40 acres, and a face 30 feet high and half a mile in length has 

 been opened. The stone is of medium texture, semi-crystalline, of a 

 water- blue or gray color. The quarries at Glens Falls, on both sides of 

 the Hudson Eiver, furnish beside the black marble already referred to a 

 great amount of dark-colored limestone which is used for tiling, etc., as 

 well as burning into lime. At Willsborough and Crown Point, in Essex 

 County, there are also extensive quarries* of blue-black limestone of 

 good quality. In various towns in Montgomery County a gray or blue- 

 gray semi-crystalline limestone is worked for building material. The 

 stone is said to be strong and durable, though care need to be used in 

 its selection. At the Indian reservation in Onondaga County a gray, 

 compact, semi crystalline limestone, said to possess great strength and 

 durability, was formerly extensively quarried, but the work has of late 

 fallen off somewhat, owing to lack of transportation facilities. A gray, 

 crinoidal stone that takes a fair polish is also found at Onondaga, in 

 the same county. 



At Lockport, in Niagara County, a fossil-bearing calcareous dolomite 

 has been quarried for many years for general purposes of construction in 

 New York and Rochester. The stone does not take a good surface and 

 consequently does not polish readily, but some portions make quite 

 showy mantels, owing to the presence of red crinoidal remains. Accord- 

 ing to Professor Julien* this stone as used in New York City has not 

 proved durable. The fault, however, he regards in part to the manner 

 in which the stone is used, about 40 percent, of the blocks being set on 

 edge. 



North Carolina. — Limestones and dolomites of good quality for build- 

 ing purposes occur in abundance in this State, but are not extensively 

 quarried for lack of a market or transportation facilities. Near New 

 Berne, Craven County, there occurs a very coarse cellular shell stone 

 of Eocene age that has been used for underpinnings and fences, but it 

 is said not to weather well. Material of the same nature, but much finer 

 in texture and more compact, occurs at Rocky Point, in Pender County, 

 and which has been used in the construction of breakwaters and other 

 harbor improvements at Wilmington, in this State. A coarse, dull red 

 dolomite occurs at Warm Springs, in Madison County, aud also light blue- 

 gray varieties, but neither are worked, as there is little demand for the 

 material. 



* Report of Tenth Census, Vol. x, p. 369. 



