MORDENITE — ROSS AND SHANNON. 

 Analysis (1) and ratios of cottony mordenite. 



Constituent. 



SiOj 



AI2O3 



CaO 



MgO 



NaaO 



K2O 



H2O+110° C. 

 H2O-110° C. 



Total.. 



Per cent. 



Ratios. 



0.119 X 9 

 .118 X 1 



.126 X 1 

 .137 X 6 



1.00 X 9 

 .99 X 1 



1.06 X 1 

 1.15 X 6 



The material of this analyzed sample was biaxial and negative with 

 the orientation XAc = 3°40', Y = a, Z = h, the indices of refraction 

 being a = 1 .470, jS = 1 .475, 7 = 1 .475, 7 - a = 0.005. 



The second sample analyzed came from a pure nodule about 8 

 centimeters in maximum diameter which has evidently been weath- 

 ered upon the surface for some time, as it is weather stained; the 

 original shell is bleached, and the mordenite is in places stained green 

 by algae. The nodule is red on its original surface from a thin coating 

 of heulandite, succeeded inward by a thin shell of chalcedony, inside 

 which the mass consists of pure mordenite in fibers extending from 

 all sides toward the center. The fibers are straight and close packed 

 and reach a maximum length of 2 centimeters. The color is creamy 

 white and the luster, on fresh fracture, is faintly silky. The analysis 

 gave the following results : 



Analysis {2) of weathered fibrous mordenite nodule. 



Constituent. 



Si02 



AI2O3 



CaO 



MgO 



NazO 



K2O 



H2O+110°C 

 H2O-110°C 



Total 



Ratios. 



.093 



.121 



.0631 



.012 



.057 



.006J 



.5041 



.240/ 



0.121 X 9 

 .121 X 1 



.138 X 1 

 .124 X 6 



1.00 X 9 

 1.00 X 1 



1.13 X 1 

 1.02 X 6 



The refractive indices of this sample, measured on the analyzed 

 material are : a = 1 .472, ^ = 1 .475, 7 = 1 .476, 7 - a = 0.004. All of the 

 fibers which are thick enough to have appreciable birefringence were 

 found to have a small inclined extinction. 



Many of the specimens received are amygdules free from matrix 

 which apparently were gathered, like so many pebbles, from the 



