ABT. 19. 



MOEDENITE — ^ROSS AND SHANNON. 



17 



(1) Challis analyzed chlorite (Ross). 



(2) ChaUis blue-green chlorite (Ross). 



(3) Nova Scotia, analyzed chlorite of Walker (Larsen). 



(4) Bergen Hill, New Jersey, diabantite (Larsen, Bull. 679, U. S. G. S., p. 67). 



(5) Plamfield, New Jersey, diabantite (Larsen, BuU. 679, p. 67). 



(6) Delessite (Larsen, BiOl. 679, p. 255). 



The results show the marked variabihty in optical properties as 

 well as in composition of the materials which have been referred to 

 diabantite and delessite. Examinations of new occurrences of these 

 minerals can scarce do more at present than to add accurate data 

 to the literature that it may in the future be available for use in the 

 interpretation of the groups as a whole. 



CALCITE (ARGENTINE). 



Several specimens of calcite are included in the Challis material 

 with the statement that they come from the centers of the larger 

 mordenite geodes. These are all of the unusual variety of calcite 

 which shows lamellar or platy structure and parting parallel to the 

 basal pinacoid (0001), and which is commonly given the varietal 

 name "argentine." The largest specimen of this argentine received 

 has plates 16 centimeters in diameter and while containing quartz 

 and analcite shows no mordenite. Another large specimen, shown 

 in plate 3, lower, is evidently a solution remnant and includes analcite, 

 quartz, and mordenite. A third specimen, in which the platy char- 

 acter is not so evident, is a rounded cast of the central portion of a 

 geodal cavity and is coated on the outside with fibrous mordenite. 

 When clean cleavages from the interior of this mass are dissolved in 

 acid,longsilkyneedles or mordenite remain behind. The broadly platy 

 specimens are snow-white in color. The characteristic pearly luster 

 on the basal pinacoid, usually shown by argentine, is lacking, doubt- 

 less because the plates have a uniform thin coating of peculiarly 

 reticulated quartz. A specimen in the United States National 

 Museum from Republic mining district, Washington, is identical 



