No. 75.] 



129 



diffused through them, like the masses of anthracite found in those from 

 Herkimer county. Occasionally they appear almost like crystals of 

 specular iron itself, but with the form of quartz. It is probably to the 

 disintegration of this ore that the ochrey and cavernous appearance of 

 these crystals is to be ascribed. 



The Natural bridge, in Lewis county, has furnished opaque crystals 

 of quartz of considerable size, and presenting some interesting modifi- 

 cations. To those already given, I can now add that which is here 

 figured, and which is remarkable, as exhibiting only three terminal 

 faces. 



According to Vanuxem, hyalite is found in the Potsdam sandstone, 

 half a mile below Canajoharie, in Montgomery county. Report on the 

 Geol. ^th Dist., p. 29. 



TABULAR SPAR. 



(Mineralogy of New- York, page 270.) 



Dr. Emmons states that fine specimens of this rather rare mineral are 

 found in Keene, Essex county. Geology of the 2d Dist., p. 286. 



NEMALITE. 



(Mineralo<i:y of New-York, page 272.) 



Prof. Connell has recently analyzed this mineral. His results are 

 very different from those of Dr. Thomson, but he operated upon a very 

 small portion. They are as follows, viz : Magnesia, .57*86; protoxide of 

 iron, 2-84; silica, 0-80; water, 27-96; carbonic acid, 10*00 ; = 99-46. 

 He supposes the formula to be, 5 Mg O, HO + MgO, CO2HO. 



[Senate, No. 75.] 9 , 



