山形縣赤山鑛山産銅鑛石の熱的研究〔第2報〕

抄録

In a rec ?? nt paper, the writers reported the result of thermal experiments on the lattice intergrowth of chalcopyrite in bornite from the Akayama mine.
During their experiments, it was found that:
(1) Massive or granular chalcopyrite is also absorbed partly by bornite at 350°C in 30 hours, at 400°C in 8 hours or at 450°C one hour to form skeleton, dendritic and worm-like structures.
(2) Covellite-chalcocite veinlets in bornite disappear to form bornite-chalcocite solid solutions at 300°C 157 hours, at 350°C 50 hours, at 400°C 6 hours, 430°C 2 hours or at 40°C one hour.
(3) Covellite-chalcocite veinlets in chalcocite also react to form bornite at 300°C 100 hours, at 350°C 24 hours, at 400°C 5 hours or at 420°C one hour.
(4) Fine granular pyrite newly appears in bornite or chalcopyrite, traversed by covellite-chalcocite veinlets, at 300°C 100 hours, at 350°C 10 hours or 370°C one hour.
From these results, the writers infer that:
(1) Aggregation of bornite, and granular chalcopyrite from this mine was formed at temperatures lower than 350°C.
(2) Covellite-chalcocite veinlets were formed at temperatures lower than 300°C, probably at much lower temperatures.
(3) The Akayama deposit has suffered no metamorphism at temperatures higher than 300°C.
(4) When a sulphide deposit suffer thermal metamorphism, the temperature can be infered from the change of mineral composition.