Vol. 5] 



Eakle. — Calcite from Terlingua. 



91 



No. 



Letter 



Symbol 

 Gdt. Miller 



<, 



Me 



b 



jisured 



P 





Ca 



loulated 



P 



1 



C 







001 







00 







00 







00 







00 



2 



b 



Occ 



010 







00 



90 



00 







00 



90 



00 



3 



a 



ccO 



100 



90 



00 



90 



00 



90 



00 



90 



00 



4 



in 



cc 



110 



90 



00 



50 



50 



90 



00 



50 



49 



5 



X 



2cc 



210 



90 



00 



67 



50 



90 



00 



67 



49 



6 



n 



ioc 



530 



90 



00 



63 



46 



90 



00 



63 



56 



7 



V 



: "ioc 



320 



90 



00 



61 



38 



90 



00 



61 



28 



8 



X 



cc 3 



130 



90 



00 



22 



10 



90 



00 



22 



14 



9 



d 



1 



102 



90 



5 



38 



49 



90 



00 



38 



51 



10 







01 



011 







13 



52 



38 







00 



52 



43 



11 





1 



111 



50 



51 



64 



27 



50 



49 



64 



18 



12 



f 



i 



3 



113 



50 



45 



34 



36 



50 



49 



34 



43 



CALCITE FROM TERLINGUA, TEXAS. 



Occurrence. — Excellent specimens of calcite have recently 

 been found in the Terlingua cinnabar mine and a couple of them 

 have been presented to the department by Mr. Wilke. This mine 

 is the one from which the new mercury minerals Eglestonite, Ter- 

 linguaite, and Montroydite came. 14 The specimens are reddish 

 calcareous rock coated with a layer of clear lustrous calcite crys- 

 tals, which are interesting because of the number of rarer forms 

 present. The crystals have a pale yellowish tinge and occasion- 

 ally include specks of cinnabar. A few larger crystals of a sec- 

 ond generation occur lying upon the calcite coating, which have 

 the same habit as those of the first generation. The crystals 

 forming the coating are fairly uniform in size, averaging 5 mm. 

 in diameter, and all stand vertically on the rock, showing the 

 complete upper half and portions of the lower half of the crys- 

 tals. The few crystals of the later growth lie more on their sides 

 and show both ends. They have a deeper yellowish tinge. 



Habit. — One habit characterizes all the crystals, namely, a 

 large negative rhombohedron -2R with much smaller faces of 

 the other forms grouped about its edges. Fig. 3 shows the gen- 

 eral habit and most of the forms. 



Forms. — The forms observed on the crystals are given in the 

 following table. Notwithstanding the great number of forms 

 possessed by calcite, a new scalenohedron 3E -V" is present. 



u Amer. Journ. Science, 1903 (4), 16, 251-261. 



