Chemical Examination of American Minerals. 83 



The constituents of the purest looking part of the speci- 

 men were found to be. 



Silica, 37-808 



Alumina, 25-104 



Lime, 18-336 



Protoxide of iron, 7-892 



Potash, 7-305 



Water, 1-500 



97-945 



Were we to consider these constituents as all belonging to 

 the chemical constitution of the mineral, it would be a com- 

 pound of, 



9 atoms silicate of alumina, 



3i atoms silicate of lime, 



1^ atoms silicate of iron, 



1 atom silicate of potash. 



Which of these constituents are only accidental, and which 

 are essential to the constitution of the mineral, can only be- 

 come known, when Nuttallite from different localities shall 

 have been subjected to examination. 



Note. This mineral was noticed by Dr. Wm. Meade about 

 four years ago, in Silliman's Journal, vol. vii. p. 52, under 

 the name of elaolite. The specimens examined by Mr. 

 Brooke, it appears, were imperfectly crystalized, so that the 

 structure of the mineral could not be determined with great 

 accuracy. I have seen it in very perfect, though minute, rec- 

 tangular prisms, terminated by four-sided pyramids, which 

 afforded measurements by the reflecting goniometer very simi- 

 lar to those of scapolite. 



