4 BALCH, ON THE 



was present. Moreover, although not enough of the vein re- 

 mained for accurate observation, I was of opinion that it was 

 not peculiar to chance boulders, but a true vein in the ledge. 



An analysis, performed at that time, (Sept , 1858,) afforded 

 me results, which, as they have never been published, are given 

 below : 



Silicic Acid 37.69 



Alumina , . . . 32.31 



Soda 24 80 



Chlorine 6.17 



Ferrous Oxyd -. trace. 



This agrees well with the recognized formula for Sodalite, 

 3 (NaO Si0 2 +A1 2 3 Si0 2 )+ Na Cl, except that the amount 

 of Chlorine is a little too low. 



In April, 1862, while examining the ledges on the left hand 

 of the road I discovered quite an extensive vein of elaeolite, 

 situated about 10 rods N. W. from the old locality, and nearly 

 at right angles with it. This new vein varies in width from a 

 few inches to a foot, or more, and runs irregularly along the 

 face of the ledge for 30 or 40 feet. It is composed of orthoclase 

 and greenish elaeolite, large imperfect crystals of black horn- 

 blende, biotite, zircon, flakes and filiments of graphite and 

 several other minerals in small quantity ; there is no sodalite 

 near the surface; it first begins to appear at the depth of 1| 

 2 feet. This vein was blasted in its widest part this autumn 

 by Mr. C. H Higbee and myself, and yielded us some very fine 

 specimens of sodalite, varying in colour from violet to azure 

 blue, and subtransparent. I have analysed carefully selected 

 specimens of both sodalite and elasolite from this vein with the 

 following results : 



Sodalite; very dark blue. Sp. Gr=2.30. Two portions 

 a. and b. were analysed. 



a. b. Results. 



Si0 2 37.64 37.44 37.54 



A1 2 3 32.13 32.16 ' 32.15 



NaO . 24.57 18.94 



Ca 0. .35 .35 



Na. 4.18 4.18 



Cl 6.45 6-45 



99.61 



