Quick
Search: 		  
advanced search
 GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help 
Economic Geology Email Content Delivery
JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Economic Geology; November 1961; v. 56; no. 7; p. 1273-1296; DOI: 10.2113/gsecongeo.56.7.1273
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Yund, R. A.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

Phase relations in the system Ni-As

R. A. Yund

Phase relations in the system Ni-As were determined in rigid silica-glass tubes, in collapsible Au tubes, and by differential thermal analyses. The system includes the well established minerals maucherite (Ni 11 As 8 ), niccolite (Ni 1 + or -xAs), and NiAs 2 polymorphs rammelsbergite and pararammelsbergite. A phase with the composition of Ni 3 As (dienerite) could not be synthesized, and if this phase exists it must be stable only below 200 degrees C. Ni 5 -xAs 2 is stable to approximately 993 degrees C. and has a large variation in its Ni/As ratio. Maucherite, which is essentially restricted to Ni 11 As 8 composition, melts incongruently at 830 degrees + or -5 degrees C. to niccolite plus a liquid. The existence of a metastable form of Ni 11 As 8 appears to be likely. Niccolite, which is stable to 962 degrees + or -3 degrees C., also has a large variation in its Ni/As ratio. The niccolite solvus between NiAs and NiAs 2 is not useful as a geothermometer, however, since it is nearly vertical in the temperature range of geologic interest. The pararammelsbergite-rammelsbergite inversion was found to occur at 590 degrees C. under the vapor pressure of the assemblage when pure NiAs 2 is in equilibrium with niccolite. The inversion temperature is raised 22 degrees C./1000 bars, giving a H of 0.57 Kcal/mole at 590 degrees C. When pure NiAs 2 is in equilibrium with metallic As instead of niccolite, the inversion temperature is approximately 8 degrees C. higher. Investigation of the inversion temperatures of natural specimens of rammelsbergite and pararammelsbergite shows that solid solution of elements such as Fe, Co, and S may lower the inversion by more than 100 degrees C.

This record provided courtesy of AGI/GeoRef.




This article has been cited by other articles:


Home page
 Eur J MineralHome page
E. Makovicky and S. Merlino
OD (order-disorder) character of the crystal structure of maucherite Ni8As11
European Journal of Mineralogy, August 1, 2009; 21(4): 855 - 862.
[Abstract] [Full Text] [PDF]

Home page
 Economic GeologyHome page
J. J. Hanley
THE ROLE OF ARSENIC-RICH MELTS AND MINERAL PHASES IN THE DEVELOPMENT OF HIGH-GRADE Pt-Pd MINERALIZATION WITHIN KOMATIITE-ASSOCIATED MAGMATIC Ni-Cu SULFIDE HORIZONS AT DUNDONALD BEACH SOUTH, ABITIBI SUBPROVINCE, ONTARIO, CANADA
Economic Geology, March 1, 2007; 102(2): 305 - 317.
[Abstract] [Full Text] [PDF]

Home page
 Mineral MagHome page
P. Bayliss
Dienerite - a mystification
Mineralogical Magazine, October 1, 2001; 65(5): 685 - 687.
[Abstract] [Full Text] [PDF]


JOURNAL HOME HELP CONTACT PUBLISHER SUBSCRIBE ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2010 by Society of Economic Geologists