Flexible Marble. 



301 



crystallized, or as rhomb spar : in Bennington, Adams, Lee, Pitts- 

 field, Stockbridge, Great Barrington, New Marlborough, Sheffield, 

 and indeed in nearly every town in the county, it occurs either 

 coarsely granular, and of a crystalline structure ; or so finely granular 

 as to be pulverulent. This latter variety, which is genuine dolomite, 

 abounds most in the south part of the county, especially in Sheffield, 

 where, according to Prof. Dewey, it is sometimes fetid. In Canaan in 

 Connecticut, which lies contiguous to Sheffield, this dolomite, which 

 is of a snowy whiteness, disintegrates abundantly ; leaving in many 

 places, loose crystals of white augite and tremolite, which have fallen 

 out. In other places, as in Stockbridge, it is of a gray color. 



This appears to be the oldest variety of magnesian carbonate of 

 lime that has been found ; corresponding to that described by Beu- 

 dant, as occurring in St. Gothard, interstratified with mica slate.* 



A considerable proportion of the limestone in West Stockbridge, 

 Lanesborough, and New Ashford, is flexible and elastic. Slabs 

 of it a few feet long, and from one to two inches thick, show 

 these properties very distinctly by supporting the ends, especially if 

 they are thoroughly wet. Generally the grain of this variety is 

 coarse and the structure rather loose ; though sometimes it is fine 

 grained. Usually it is white, slightly tinged with red ; but some- 

 times gray and dark colored. According to Prof. Dewey, it is the 

 common, and not a magnesian carbonate. The slab in the collection 

 (No. 501) is from New Ashford; where it is abundant. Its peculiar 

 properties seem to depend upon the agency of water : and there are 

 numerous facts that render it probable, that many of the rocks in the 

 interior of the earth are rendered soft and flexible by this same 

 agent : so that although marble and sandstone that will retain their 

 flexibility after being quarried, are rare, yet probably deep in the 

 earth's crust they are abundant. 



The non-magnesian as well as the magnesian carbonate of lime 

 in this county, is often fetid. In Stockbridge, this is sometimes the 

 case with that which is white and coarsely granular : in Williams- 

 town, this variety is dark colored and fine grained, and in Benning- 

 ton, it is nearly black. 



The origin of the fetid odor in limestone, quartz, &c. has been va- 

 riously explained. The natural explanation imputes it to animal 

 matter, which has been imprisoned since the original formation of 



* Mineralogie, Tom. 1, p. 592. 



