216 Geology, ^c. of the Connecticut. 



19. Chalcedony. 



1. Common Chalcedony. At East-Haven, in greenstone. 

 {Silliman.) Also in the same rock at Southington, Far- 

 mington, Hadley, Sunderland, Deerfield, Greenfield, Gill, 

 and indeed, in almost every greenstone hillock ar\d ridge 

 from New-Haven to Gill. Its color is light grey, deep grey, 

 brownish, yellowish and greenish grey; it occurs botryoi- 

 dal, mammillary, cylindrical and reniform, and is often of a 

 cloudy or milky appearance, and frequently, strongly trans- 

 lucent. 



2. Cacholong. In greenstone, Deerfield. It is associated 

 with common chalcedony, and frequently, envelopes it, or 

 constitutes some of the bands of agates. Its color is milk 

 or yellowish white. 



3. Carnelian. In greenstone, Deerfield. United with 

 common chalcedony and cacholong, into which it passes. 

 Its color is usually pale or yellowish red. It is not abundant. 

 Also at East-Haven. 



4. Sardonyx? Some specimens of the carnelian in Deer- 

 field greenstone, being reddish yellow and orange, appear 

 to belong to this variety ; but it occurs in so small quantities 

 as hardly to be worth noticing. 



Agate. This occurs at East-Haven and Deerfield ; and 

 as it is composed of varieties of chalcedony and quartz, this 

 seems to be the proper place to notice it. A description of 

 a part of the agates occurring in these localities has already 

 been given with sufficient minuteness in the American Jour- 

 nal of Science, and in Cleaveland's Mineralogy. But since 

 the publication of those accounts. Dr Dennis Cooley has 

 discovered a new locality in the Deerfield greenstone, from 

 which he has obtained specimens so much superior to those 

 heretofore found that they deserve a particular notice. The 

 following is a description of specimens in his possession. 



No. 1. Longer diameter of the face of the agate, nine 

 inches — shorter diameter, six inches. Outer zone, greenish 

 chalcedony, half an inch broad. Second zone chalcedony, 



