SIXTH REPORT OF THE DIRECTOR ICJOO, 



201 



LETTER 



ANGLE 



NUMBER OF 

 READINGS 



MEASURED 



CALCULATED 









/ 



/ 



: d 



111 : 101 



12 



35 19 



35 16 



: q 



111 : 133 



8 



22 H 



22 



:k 



111 : 255 



9 



19 4 



19 28 



qr . ipir 



711 : 711 



2 



16 2 



16 6 



a :¥ 



100 : 711 



12 



11 17 



11 25£ 



Gypsum 



Garbutt, Monroe co. 

 Among a number of specimens collected in the spring and 

 summer of 1909 from the gypsum region of western New York by 

 Mr Henry Leighton, assistant in economic geology, was a suite of 

 12 specimens of crystallized gypsum 

 which furnished crystals compara- 

 tively rich in forms. The specimens 

 in question were collected from the 

 mine of the Garbutt Gypsum Co., and 

 from No. 2 mine of the Lycoming 

 Calcining Co>., botfh situated at Gar- 

 butt, Monroe co. The gypsum crys- 

 tals occur in narrow seams in massive 

 gypsum and are sometimes associated 

 with crystalline sulfur of remarkable 

 purity and transparency. The crys- 

 tals are colorless, transparent and 

 average 5 millimeters in length 

 parallel to the positive unit pyramid. 

 In crystal habit, they conform closely 

 to the type shown in figure 5. The 

 prismatic zone is particularly rich in 

 forms, yielding 8 of the 12 prisms re- 

 corded for gypsum. 1 Two rare neg- 

 ative pyramids in the zone [010.101] were noted, present either 

 together or alternating on all 12 of the crystals measured. These 



Fig. S Gypsum, Garbutt 



1 Goldschmidt, V. Krystallographische Winkeltabellen. Berlin 1897. 

 Luedecke, O. Minerale des Harzes. Berlin 1896. 2>77- 



