PLATE I. 



Fig. 



1. Initial form of pit, Actinolite type (110), HF. X 300. 



2. Mature pit of the Actinolite type (110), HF. X 300. 



3. Another form of the mature pit of tlie Actinolite type (110), HF. X 300. 



4. A rather exceptional variant on the normal Actinolite type (110), distin- 



guished by a well defined fourth figure-face at tlie lower end, HF. 

 x300. 

 6. Initial form of the Wolfsberg sub-type (110), HF. x 1800. 



6. The Wolfsberg sub-type (110), HF. x 300. 



7. Compound stepped etch-pit of the Wolfsberg sub-type (110), HF. X 300. 



8. Exceptional pit of the Wolfsberg sub-type, showing a fourth figure-face at 



the lower end (110), HF. x 300. 



9. Immature pit of the Kragero sub-type (110), HF. x 300. 



10. Matured pit of the Krageru sub-type (110), HF. X 300. 



11. Another form of the last on another Hornblende variety, showing the com- 



mon occurrence of a fourth figure-face at the lower end of tlie pit. X 300. 



12. An exceptional pit found on (110), along with the pits of Figure 11. X 300. 



13. The Edenville sub-type (110), HF. x 600. 



14. Another form of the last, where the individual figure-faces can no longer 



be distinguished. X 600. 

 15 and 16. Two forms of the Glaucophane type (110), HF. X GOO. 

 17. The Crossite type (110), HF. x 1000. 



18 and 19. Two forms of the Kiebeckite type (110), HF. x 1000. 

 20. The type of pit on Barkevikite (110), HF. X 300. 

 21 and 22. Two forms of the pits on Arfvedsonite (110), HF. X 175. 

 23a, 236, 23c. Pits on (010) of Actinolite, HF. 23a is the "light" etch-pit, the 



other two the "dark" pits simultaneously occurring with the first, 



HF. X 300. 

 24. The modification of the normal pit on Actinolite (110) by the admixture 



of h% sulpliuric acid to the commercial hydrofluoric acid generally used. 



X300. 

 25a and 256. The same as the last, except that the admixture is here 50% of 



sulphuric acid. X 300. 



26. The type of pits on (010) of common and basaltic (aluminous) Hornblendes, 



HF. X 300. 



27. A pit on (100) of Actinolite (non-aluminous amphibole), HF. X 300. 



28. A pit on (100) of basaltic Hornblende (aluminous), HF. X 300. 



29. Caustic soda pit on (100) of basaltic Hornblende. X 300. 

 80. Pit on (TOl) of basaltic Hornblende, HF. X GOO. 



31. Pit on (fOl) of Actinolite and other non-aluminous amphiboles, HF. X 300. 



32 and 33. Caustic soda pits on Actinolite (110). X 1200. 



34a and 346. Caustic soda pits on basaltic Hornblende (110). X 300. 



85a, 356, and 35c. Caustic soda pits on the Kafveltorp Hornblende (110). X 600. 



36a, 366, 36c, and 36c?. The various types of pits produced on Anthophyllite 



and Gedrite, (110), HF. X 3000. 

 37a and 376. Pits on Aenigmatite (110), HF. X 3000. 



