Grdywdcke. 



33 



exists. As yet, however, the working of it has hardly commenced ; 

 although almost every man is aware of the value of this rock ; and 

 there are few who do not sometimes stand in the need of it for eco- 

 nomical purposes. As the facilities for transportation are multiplied, 

 and particularly in the mountainous part of the state, its use will un- 

 doubtedly be greatly extended. At present I believe, the shops in 

 Boston are supplied from Vermont and New Hampshire. 



Graywacke, 



For the most part, this rock furnishes a coarse stone only fitted for a 

 common wall ; but sometimes its stratification is so regular, and its 

 grains are so fine, that it answers well for underpinning, step stones, 

 &c. It is quarried I believe in Brighton, and some other towns in the 

 vicinity of Boston. At Pawtucket, on the R. I. side of the river, is 

 an extensive quarry of a fine grained and slaty variety, which I should 

 judge would form a good nagging stone ; and immense quantities have 

 been taken away for this object and for other purposes. On Canon- 

 icut island in that state, is also a valuable quarry of this rock. 



Graywacke is sometimes beautifully amygdaloidal ; that is, it con- 

 tains numerous rounded or almond shaped nodules of some other 

 mineral. In these instances, however, the case of the rock is rather 

 Wacke, than graywacke. This wacke (which resembles indurated 

 clay,) often forms the cement of graywacke. In Brighton it is of a 

 reddish color, while the imbedded nodules are sometimes white, and 

 sometimes white feldspar with epidote, which is of a lively green co- 

 lor ; and these substances are not only in rounded masses, but in veins 

 of irregular shape. The rock is hard and admits an imperfect polish. 

 It then resembles porphyry and is elegant. A fine example of this 

 may be seen at the residence of H. A. S. Dearborn, Esq. in Roxbury, 

 forming a pedestal for the bust of his father. It is only slightly pol- 

 ished, but would generally be mistaken for porphyry. 



A similar amygdaloid occurs in Brookline, Newton and Need- 

 ham. A variety still more beautiful is found at Hingham. The col- 

 or of the base is chocolate red ; and the nodules are red, green and 

 white. I do not know whether large blocks can be got out. 



I think upon the whole, however, that the finest amygdaloid occurs 

 in Saugus, on the hill a few rods east of the meeting house. The 

 base is a pleasant green, and the nodules white, compact feldspar, 

 generally spherical, and thickly interspersed. I have little doubt that 

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