14 L. H. Borgström. 
TABLE XV. 
. 
Dissociation point of some minerals 
(CC HalcopYynEEeN GUESS ES RN ER 620? 
Tennantiter AT CMS Stas SIS arne lsd oss ahr 630” 
PYTT MES Mets rele ere a Sea SN de RTL 690? 
ANNES EINO DNB OR LIE ASKS te Stef ske rele ls fee la ee 700? 
(rlatteo dORN(COIIOAS SPEER 660”—700?” 
The dissociation points of all these minerals are pro- 
bably above 800”—1000” at a pressure of 60 atmospheres. 
This explains the fact that pyrite, chalcopyrite and arseno- 
pyrite are met included among the primary constituents of 
eruptive abyssal rocks. 
