What is KUROKO?


Volcanic-hosted feature is shown in the occurrence. A typical Kuroko deposits are underlain by extensive acidic volcanics where the feeder stockwork or veins exist in the strongly silicified part of the volcanics.





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Yellow ore is characterized by Pyrite-Chalcopyrite assemblage.

Black Ore is mainly composed of sphalerite and Galena with subordinate amounts of Chalcopyrite, Tetrahedrite and gold and silver minerals.




Strata-bound evidences are shown in the stratigraphic position where the typical Kuroko deposit is hosted within the unit of distinctive volcano-sedimentary sequence which is constituted of the footwall dacite lava and the pyroclastics and the hangingwall mudstone intercalated in pumice to lapilli tuff.

 

 

 

Massive sulfide and sulfate ore bodies are comprised of proximal and distal types. Strictly speaking, the term of massive sulfide should be used only for the proximal ore , because the distal ore has much sedimentary features such as size grading of ore and alternative banding of ore seam and mudstone.





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Siliceous black ore is also composed of sphalerite and galena. The ore is located in the footwall unit as a disseminated or stockwork type which is usually distributed in the peripheral part of a unit ore body.

Siliceous Yellow ore is economically same mineral composition , but different mode of occurrence to the yellow ore. Ordinary disseminated to stockwork sometimes vein or veinlets ore is observed in the footwall rocks directly under the massive sulfide.








Polymetallic feature is characterized by many kinds of constituent minerals; sphalerite, galena, chalcopyrite and pyrite associated with subordinate amounts of tetrahedrite and Ag-minerals with much useful minor or rare metals as impurity such as Antimony, Thallium, Gallium and so on.

 

 

 

Submarine environment is proven by the existence of sediments with marine fossils and basalt lava with pillowed structure overlying ore body. Sedimentary structure such as graded bedding or imbricate fragments of ore with sediment are often recognized in the distal ore.


 

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