GEOLOGICAL AND MINERALOG1CAL 

 NOTES, No. I. 



SODALITE. 



BY JOHN H. SEARS. 



THE discovery of this rare silicate was first brought 

 into notice in Essex county by Gilbert L. Streeter, Esq., 

 in October, 1855. The locality of the discovery as de- 

 scribed is on the right hand side of the road leading along 

 Collins Cove from the Salem Alms House to Hospital 

 Point. This mineral, when first described, was called can- 

 cranite. Later it was analyzed by Mr. David M. Balch 

 and proved to be sodalite. 



It was found in veins of syenite, which is composed of 

 plagioclase, feldspar, hornblende, elaeolite, biotite mica 

 and magnetite iron, with accessory minerals of zircon, ap- 

 atite, quartz, albite, augite and small crystals of ortho- 

 clase. This sodalite is of a rare occurrence, and seems 

 to be in pockets in narrow veins. From my own obser- 

 vations, I have found it only where these narrow veins, 

 three or four inches wide, are cutting through porphyritic 

 diabase. In these pockets it is quite plentiful, coloring 

 the rock in blotches of pink and blue. 



In April, 1862, Messrs. D. M. Balch and C. H. Higbee 

 blasted in a vein of the elaeolite zircon syenite that was 

 discovered ten rods N. W. of the old locality, when spec- 

 imens of the sodalite and elaeolite were obtained. These 



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