ON CALAMINE CRYSTALS FROM MEXICO, RUTILE-MICA 

 INTERGROWTH FROM CANADA, AND PSEUDOMORPHS 

 OF MARCASITE AFTER PYRRHOTITE FROM PRUSSIA. 



By Joseph E. Pogue, 



Assistant Curator, Division of Mineralogy, U. S. National Museum. 



1. CALAMINE CRYSTALS FROM CHIHUAHUA, MEXICO. 



Calamine crystals of unusual perfection from Chihuahua, Mexico, 

 acquired in April, 1910, by the United States National Museum (Cata- 

 logue No. 86662), show the following faces: c(OOl), 6(010), m(llO), 

 6(011), ^(031), s(lOl), ^(301), ^(211), and ^(121), the last appear- 

 ing only on the antigolous pole. The crystals are clear and colorless, 

 with tabular development parallel to 6(010), and vary in size up to 

 11 by 4 by 1 mm. for their greatest dimensions. Figures 1, 2, and 3, 

 plate 63, show the actual development of three individuals, at the 

 same time representing the three phases or habits to which all 

 the crystals may be referred. Phase 1, of which figure 1 is typical, 

 often lacks the base c(OOl) and is chiefly characterized by a 

 symmetrical development, the presence of '^(211), and a wedge- 

 like top elongated parallel to the a-axis owing to a prominent 

 development of the brachydomes. Crystals from the Organ Moun- 

 tains, Dona Ana County, New Mexico, ** and from Altenberg, Bel- 

 gium,^ resemble this phase. Occasionally the two pairs of domes 

 are almost equally developed, a resulting squarish cast being then 

 given the crystal. Phase 2, represented by figure 2, is terminated at 

 its lower end in only one instance ; aside from this, its chief charac- 

 teristics are the pointed character of its apex, its rather unsymmetri- 

 cal development, and relatively great length. Phase 3, as shown in 

 figure 3, has a wedge-like upper termination, formed by the prominent 

 development of the macrodomes s(lOl) and t(S01), to the almost 



«W. E. Ford and F. Ward. Calamine crystals from the Organ Mountains, Dona 

 Ana County, New Mexico. [In Mineral Notes.] Amer. Jour. Sci., vol. 28, 1909, 

 pp. 185, 186. 



bC. Hintze. Handbuch der Mineralogie, vol. 2, 1897, pp. 1317-1319. 



Proceedings U. S. National Museum, Vol. 39— No. 1801. 



571 



