Am. Jour. Sci., Vol. XIX, 1905 



1 



Plate I. 





1. Original Albite (Mitchell Co.), x 10. 2. Fragment of same heated to 1200°, 

 x20. 3. Another fragment, 1206°, x 20. 4. Another, 1225°, x 20. 5. Another, 



1250°, x 20. 6. Another ( x 800) four hours at 1125°. 7. Another, bent at 1200°, 

 x 10. 8. Microcline bent at 1200°, x 10 ; note the direction of cleavage (cf. dotted 



line). All the photographs were made through crossed nicols, vitreous areas are 



therefore black. 



