. BUILDING AND ORNAMENTAL STONES 467 



fine work can be obtained are at Lancaster, in Worcester Connty. This 

 quarry is stated by Marvin* to have been opeued by a Mr. Flagg over 

 a century ago, and the slates were in use as early as 1750 or 1753 (ante, 

 p. 291). Owing to lack of favorable transportation facilities the work 

 was discontinued more than fifty years since, and it was not till 1877 

 that it was recommenced. The slate though porous is said to hold its 

 color well and to be durable. Another outcrop of slate of good quality 

 is said to occur about 1 mile north of Clinton, in this same county. It 

 is not, however, as yet quarried. 



The clay slates occurring in the vicinity of Boston and Cambridge 

 have long been used for road materials, but for purposes of construction 

 only to a slight extent. They are not sufficiently fissile for roofing pur- 

 poses. The stone is regarded by Professor Shaler as of great value for 

 rough building, as it is durable, easily quarried, and very effective when 

 placed in a wall. The Shepherd Memorial Church in Cambridge is the 

 only building of importance yet constructed of this material. 



Minnesota. — At Thompson, Carlton County, where the Saint Paul and 

 Duluth Railroad crosses the Saint Louis Elver, there occurs, according 

 to Prof. N. LI. Winchellt an inexhaustible supply of hard, black, and 

 apparently eminently durable slate suitable for roofing, school-slates, 

 tables, mantels, and all other purposes to which slate is usually applied. 

 Quarries were opened here by the railroad company in 1880, but for 

 some unknown reason were discontinued before any of the stone had 

 been put upon the market. The deposit is regarded as of especial value 

 by Professor Winchell, inasmuch as it is the most western known in the 

 United States, and its close proximity to the railroad renders the trans- 

 portation of the quarried material a matter of comparative ease. 



Michigan. — An extensive deposit of Hurouian slates occurs in the 

 northwestern portion of the northern peninsula of this State, princi- 

 pally in the towns of Houghton, Marquette, and Menomonee. But a 

 small portion of the entire formation will furnish material sufficiently 

 fissile, homogeneous, and durable for roofing purposes; nevertheless 

 the supply of good material is so abundant as to be practically inex- 

 haustible. At L'Anse the beds extend down to the lake shore, but 

 are badly shattered, not homogeneous, nor or' sufficient durability in 

 this immediate vicinity to be of value. Good roofing slate is, however, 

 found about 15 miles from L'Anse, on the northwestern side of the 

 Huron mountain range, and about 3 miles from Huron Bay, where ex- 

 tensive quarries have been opened. The stone here is susceptible of 

 being split into large, even slabs ot any desired thickness, with a fine 

 silky, homogeneous grain, and combines durability and toughness with 

 smoothness.' Its color is an agreeable black and very uniform. Sev- 

 eral companies have located their quarries along the creek which runs 

 parallel with the strike of the slate, and a tramway about 3£ miles in 



* History of Lancaster. 



t Preliminary Rep. on the Building Stones, etc., of Minnesota, 1380, p. 17. 



