PALACHE. EPIDOTE CRYSTALS FROM ALASKA. 535 



and so developed as to present no re-entrant angles. Here as in all 

 the twin crystals the reversal of direction of the striations on 010 in 

 the twinned crystal is the easiest means of recognizing the composite 

 nature of the group. 



Figures 2 and 2a are orthographic projections of the same crystal on 

 the orthopinacoid and the clinopinacoid respectively. They represent 

 the largest crystal studied in natural size, and show how irregularly the 

 two twinned crystals are sometimes united — in this case an imperfect 

 penetration having taken place. The upper surface of this crystal is 

 bounded by cleavage planes parallel to c where the crystal was broken 

 from its matrix. 



The remaining figures (3 to 7) are orthographic projections on the 

 clinopinacoid. 



Figure 3 is another tabular crystal in which the larger portion of 

 the crystal is a single individual. Rarely such tabular crystals are 

 untwinned. 



Figures 4 and 5 are two very symmetrical twin crystals, both pris- 

 matic parallel to the axis b and doubly terminated. They show many 

 of the less common forms and the re-entrant angle between two faces of 

 n which is not common on these crystals. 



Figure 6 is a type of the untwinned crystal, prismatic parallel to 

 axis b, the usual epidote habit. It is a left-hand termination. Many of 

 the smaller crystals are of this habit with varying development of the 

 planes of n and u. 



Figure 7 is a small crystal of prismatic habit but quite unlike any 

 other found in its terminal planes. 



In conclusion it may be said that this Alaska epidote ranks among the 

 finest occurrences of American crystallized minerals, and is only sur- 

 passed in the size, beauty, and complexity 6f its crystals by the epidote 

 from the Knappenwand in the Tyrol. 



MlNERALOGICAL LABORATORY, HARVARD UNIVERSITY, 



January, 1902. 



