374 



PROCEEDINGS OF TEE NATIONAL MUSEUM. 



analysis may be accidental and the percentages of these two oxides 

 probably vary reciprocally in different specimens. The close agree- 

 ment between the values found and the theoretical values is brought 

 out in the following table : 



Analyses and calculated composition of amesite. 



1. Amesite, Chester, Massachusetts, analyzed by Shannon. 

 II. Amesite, vahies to conform with formula H4(Fe,/6 Mg5/6)2Al2Si09. 

 III. Amesite, Chester, Massachusetts, analyzed by Pisani. 



CORUNDOPHILITE FROM CHESTER, MASSACHUSETTS. 



The name corundophilite was first given by Prof. C. U. Shepard 

 to a chlorite occurring in association with corundum near Asheville, 

 North Carolina. Later he referred to this species the chlorite which 

 occurred abundantly in the emery vein of Chester, Massachusetts. 

 Analyses by Genth and others have shown that the original North 

 Carohna mineral is distinctly different from that of Chester, being 

 essentially a low-iron prochlorite. The name corundophilite has 

 since been reserved to the Chester chlorite. This mineral has been 

 analyzed by Eaton, Pisani, and Obermayer, its optical properties 

 have been given b}^ Descloizeaux and Cooke, and its constitution has 

 been discussed by Tschermak.^ Despite the distinctness of the com- 

 position and optical properties of the mineral, it has been regarded 

 dubiously by many mineralogists and has been v;iriously referred to 

 clinochlore, prochlorite, chloritoid, and biotite. 



Corundopliilite occurred very abimdantly in the emery mine at 

 Chester in large and small crystals and as granular and schistose 

 masses. Hexagonal crystals often projected from the walls of 

 narrow veins in emery and corundophilite crystals frequently were 

 tipped with amesite in parallel position. Other minerals associated 

 with the corundophilite include magnetite, ilmenite, rutile, margarite, 

 and diaspore. The typical corundophilite has not been observed 

 from any other locality. 



The present examination of this mineral was imdertaken in con- 

 nection with the analysis of the associated amesite described in the 



1 For summary of previous work on this mineral and bibliography see Dana's System of Mineralogy, 6th 

 edition, p. 655. 



