硫鹽鑛物の離溶共生に關する熱的研究 : 2次的固溶體の離溶について
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In this paper, genesis of some lattice textures of ore minerals is discussed., The studies have been made by many authorities on the lattice intergrowth formed by unmixing of a solid solution, which has been primarily deposited from the fluidal solutions., However, no considoration has been made on the exsolution from the secondary solid solution, which has been produced by mutual diffusion between solid minerals., The writer has experimentaly confirmed the unmixing phenomena of the secondary solid solution as follows; 1) Some solute minerals, such as massive chalcopyrite, vein-like chalcocite or covellite, drop-like klaprothite and massive tetrahedrite, diffuse in host minerals, such as bornite, at high temrperatures from 400℃ to 500℃ and form the various solid solution 2) The solid solutions, thus obtained, can unmix upon annealing at low temperatures of about 200℃ and give some exsolution textures, such as lattice, cell and emulsion ete., The phenomena, as described above, may be expected to occur in such geological cases when some earlier minerals suffer higher temperature at later stage of mineralization or the ore bodies receive the thermal effect by igneous action., From this point of view, more attention must be given on the ore textures formed by thermal metamorphism., Explanation of Plate 1) Lattice intergrowth of chalcopyrite (light gray line) in bornite (Bo) from the Ginmu mine, Hiroshima Prefrcture., Ch, massive chalcopyrite., ×95., 2) Chalcopyrite (light gray line) lamellae unmixed from the secondary solid solution, formed by Solid diffusion between bornite (Bo) and massive chalcopyrite (Ch) at 500℃ for one hour, by keeping at 200℃ during 17 hours., ×95., 3) Lamellea, semi-cells, worm-like and dot-like bodies of Chalcopyrite (light gray line and spot), obtained under the same conditions as in 2)., Bo, bornite; Ch, massive chalcopyrite., ×95., 4) Chalcopyrite (ch) in lamellae, semi-cells and worm-like crystals, produced by annealing the secondary solid solution, same as before, at 200℃ for 16 hours., Bo, primary bornite; bo, secondary bornite formed by thermal decomposition of massive chalcopyrite (Ch)., ×95., 5) Secondary covellite (Co) replaced the bornite (Bo) from the obari mine., Ch and Kl, chalcopyrite and klaprothite lamellae unmixed from the primary solid solution respectively., ×95., Etched with KCN., 6) Crystallographic itatergrowth of bornite (light gray) and chalcocite (dark gray) obtained by slowly cooling the secondary solid solution, formed by solid reaction of bornite and secondary covellite, as showed in 5), under heating condition of 440℃ for one hour., Annealing condition, from 300℃ to 200℃ for 7 hours., Py, pyrite produced by thermal decomposition of bornite., ×300., Etched with KCN., 7) Pyrite (Py) produced by thermal decomposition of bornite at 440℃ for one hour., Be, fine lattice intergrowth of bornite and chalcocite, obtained by unmixing of the solid solution under the same condition as in 6)., ×95., Etched with KCN., 8) Myrmekitic texture formed by solid diffusion between bornite (dark gray) and wittichenite (light gray) at 400℃ during 20 hours., ×300.,
- 日本地質学会の論文
- 1953-01-25