Atacama Kozan is an underground copper mine located in the Candelaria-Punta del Cobre district, Atacama Region, Chile. Copper mineralization at Atacama Kozan is classified into two types based on the occurrence. The mantotype orebody is strata-bound mineralization formed at the bottom of the interbedded sedimentary rocks layer of the Punta del Cobre formation and has high continuity and relatively small grade fluctuations. The breccia-type orebody is mainly hosted in andesite beneath the interbedded sedimentary rocks layer. There is no clear controlling factor on breccia-type mineralization, and the ore body extends in various directions from vertical to horizontal with extremely large grade fluctuations. Shallow manto-type ore has been the main mining target, but as tunnels deepen, the production of the deep breccia-type ore is becoming increasingly important. However, the irregularity of the mineralization often causes a large difference between the estimated and actual grades, resulting in problems such as major design modification of stopes. The application of geostatistical simulation was evaluated to improve the grade estimation accuracy of block model and to understand the uncertainty of the estimation of such irregular ore body. Three models were created for the evaluation using the exploration drilling data: (1) ordinary kriging, which is currently used in Atacama Kozan, (2) sequential gaussian simulation (SGS) based on simple kriging and (3) SGS based on ordinary kriging. Using the grade control drilling results as true values, estimation accuracy of these models was evaluated based on the criteria of correlation coefficient taking logarithm, missed mineralization, false positive mineralization and estimation error. The results showed that the e-type (average of all the realizations) of SGS based on ordinary kriging improved the estimation accuracy in all the criteria. The probability of exceeding a specified threshold and the range of possible grades of stopes were also estimated from all the realizations of simulation. Comparison of the estimation with the grade control drilling results demonstrated the validity of these assessments of uncertainty by simulation.

Inkstones were once familiar and indispensable goods in daily life. However, with the advent of modern technology, demand for them has almost disappeared, resulting the rubbing mechanism of ink, which has been passed down through experience and tradition, remains largely unraveled scientifically. In recent years, there has been an increased focus on not only the protection and preservation of traditional crafts and their processing techniques, but also on the scientific investigation of their hidden value. This study employs a geological and mineralogical perspective on the micro texture and rubbing mechanism of inkstones, complementing the conventional empirical interpretation. Two deferent types of traditional inkstones from not only Japan but also China, such as slates with well-defined slaty cleavages from the accretional prism, and hydrothermally altered sedimentary rocks were investigated by the MLA, SEM, laser microscope, surface roughness measuring instrument, XRD and microscope. These techniques allowed for the visualization and digitization of the inkstone surfaces in 3D. The study revealed that an edged instrument (TEI) in slate origin inkstones is less homogeneous than previous thought. In these inkstones, quartz and feldspar, which are characteristic of the tectonic fabric, primarily act as the TEI, while illite aligns along the slaty cleavage. This facilitates not only spreading of ink particles on the inkstone’s surface but also functions as a reservoir for rubbed ink. Conversely, in hydrothermally altered inkstones such as esteemed Duanxi inkstone in China, illite, the primary constituent mineral, exhibits random orientation. (001) of illite, oriented perpendicular to the surface, functions as the TEI, while (001) of illite aligned parallel to the surface of inkstone, performs a similar rule to that of the slate origin inkstone. It has been demonstrated that illite crystals play a significant role in the rubbing mechanism of inkstone.