Metalurgia del hierro yahoo dating

metalurgia del hierro yahoo dating

Sekaimon yahoo dating. At about the same time the. The filter choke is also sometimes stamped in the same format, however use of a date code on this part. La metalurgia precolombina en América comprende la extracción y purificación de metales, así . Se cree que la sustitución de bronce por hierro y acero fue fomentada por el . «Radiocarbon dating of copper-preserved organics». Main · Videos; Gabrielle aplin alfie hudson taylor dating show dating anne curtis luis manzano dating metalurgia del hierro yahoo dating metalurgia del hierro.

The archaeological sites are found within three different rock formations, namely PzTac, K2gy y N1N2qc. Site Ujina 11 is found in PzTac light greenwhich is a andesitic sequence; Ujina 8, Ujina 9 y Ujina 10 are found in K2gy orange brownwhich is a granodiorite intrusive; and Collahuasi 37 is found in N1N2qc brownwhich is a semi- consolidated clastic deposit.

PzTac, K2gy y N1N2qc. These shafts are almost vertical.

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Estos ejes son casi verticales. These production units systematically included two related types of features: At Ujina-8, 9, 10, 11 and 12, the furnaces have a typical bench shape and are made with granodiorite blocks Figure 6.

Some furnaces are built upon at boulders, other upon naturally occurring rock benches with additional stones arranged to form the structure. From one to the other, the overall shape of the furnaces may vary, and it may be possible in the future to distinguish several subtypes.

But all share common features, particularly a significant length 4 m to 10 man orientation perpendicular to the dominant wind, and a back wall of a height not exceeding 10 cm Figure 7. The granodiorite blocks were assembled to form a base where the fuel and the ore were put, while the back wall allowed to hold the charge in position even with a very strong wind.

Each furnace was generally linked to a unique slag heap, which was located in close vicinity, but always a few meters away, in a place well protected from the wind Figure 8.

Hammers and grinding stones have also been found associated with the slag heaps, giving clear evidence of crushing activities occurring there. The remains found in production units are typical of a copper smelting activity and can be classified into five separate categories-copper ore fragments, fuel remains, copper metal, copper slags and crushing tools. It should be noted that ore pieces, metal prills and slags are not only found at the Ujina production sites, but also at the residential site of Co37, where no evidence of furnaces has been recorded.

In the paragraphs below we will present some of our results, in the following order: At Ujina-8, 9, 10, 11 and 12, the smelting furnaces have a typical bench shape and are made with granodiorite blocks.

Study of Pre-Hispanic Copper Ores from Collahuasi For this study, 40 rock fragments were collected from threre archaeological sites-namely, Collahuasi37, Ujina 8 and Ujina Modal mineralogy is shown graphically in Figure 9.

The samples contain a mixture of Cu mineralization and gangue minerals e.

Metalurgia precolombina en América

Other mineralogy is variable, with some samples containing Fe-oxides e. UJ8-m8-c, which has All samples have trace Ag-mineralogy levels above detection limits and ranging from 0. The results indicate that oxidized copper minerals -corresponding to malachite, chrysocolla and brochantite- were primarily used in the furnaces. That mineral association is present in the majority of the samples analyzed, and suggests that the ores selected come from the same source.

Furthermore, the gangue in the samples is almost exclusively quartz. It is important to note that these results do not represent the percentage of mineralization of the source, and can only be used as a guide to link these ores with their exact origin in Collahuasi District. This is because the samples are hand selected and small and are thus biased towards mineralization and not comparable to source rocks at a larger scale.

The most important impurities in the copper ores are As, Ag and Fe Figure As these impurities are present in the raw material, this would imply that they would also be present in the metallic copper produced from the reduction of those same copper ores.

metalurgia del hierro yahoo dating

Copper slags from Co37, Ujina 8 and Ujina 10 were investigated. From their external features, they appear to have been very viscous: This is confirmed in cross section by the presence of large copper prills still embedded in some samples. Copper metal could not be recovered without slag crushing, which probably occurred close to the furnaces, where slag heaps have been found. In our examination of the mineralogical structure of the slag samples, no unreacted silica was observed.

In one case UJ10 Hthe slag is totally calcium and magnesium free. Here again, almost no unreacted silica is observed. Tridymite and cristoballite crystallised instead of clinopyroxenes.

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Interestingly, this slag has the highest copper loss ca. Along with copper, silica, calcium and iron are the main constituents of the slags. This situation is very commonly encountered in the extractive metallurgy of copper. Here, most if not all of the initial charge reacted and reached the liquid state; the ternary phase diagram CaO-FeO-SiO2 can be used to approximate temperatures reached in the furnaces, and to explain the nature of the compounds that formed in the slag.

Metalurgia precolombina en América - Wikipedia, la enciclopedia libre

Optimal slags are the ones located in the olivine domain fayalite family, 2FeO. Slags from Ujina and Collahuasi are not at all in the olivine field. The silica excess can easily be seen: The absence of unreacted minerals suggests that the smelting operation lasted for quite a long time.

Copper prills Copper prills are also frequently encountered, either isolated or entrapped in slag. Thus, the composition of the metal produced in the bench-shape furnaces perfectly matches with the analytical results obtained for the copper ores, as mentioned above Figure The copper prills appear in white. A tipical Collahuasi slag globular shape and conglomerate minerals.

The three coal samples observed all displayed a high level of alteration, appearing as small areas with a shiny, vitrified appearance and, occasionally, a melted structure. The abundant presence of radial fissures on carbonized Parastrephia sp. Figure 13 is typical of coal from this taxon previously observed in other anthracological studies Joly Although the observation of a few coal samples is too meager to draw conclusions about the management and use of fuel employed in the furnaces of Ujina 10, the Collahuasi extractive metallurgy, it is however worth noting that both taxa mentioned herein are local species that have been commonly used as rewood from the pre-Hispanic period to the present day.

In the Collahuasi District, local meteorological records show that strong winds from a very steady direction are present every day Figure Pre-Hispanic metallurgists took advantage of that airstream, constructing the smelting furnaces perpendicular to wind direction Figure Discussion and Conclusions The difficulty of clearly and systematically identifying Inca and LIP is a common problem in other mining districts, for several reasons.

One of the main reasons is the particular nature of semi-permanent mining occupations of the LIP, which were impacted by occupations associated with Tawantisuyo that reshaped the prior architecture and as a result made it difficult to identify 1 the LIP, 2 the LIP in Inca times, and 3 the LIP with Inca presence. The particular nature of Co37 as a site situated in a zone with an extreme climate and without agricultural potential, means that occupations are less stratigraphically dense than those found, for example, at LIP sites in the northern and central Altiplano.

We emphasize that, as a Collahuasi mining-metallurgical site, all food had to be brought in rather than produced in situ. While acknowledging the existence of pre-Inca occupation, prior investigations have emphasized the Inca character of the site and focused excavations especially in sectors with clearly Inca architecture.

Precisely to respond to the transformations that occurred during the LIP as a result of the Inca presence at the Co37 and Ujina sites, we performed excavations in sectors D, E and F, which displayed no Inca architecture and had not been previously studied. Despite the initial goal of generating a diachronic breakdown, in all strata excavated in those sectors we observed the stratigraphic coexistence of ceramics from the LIP and Inca periods Uribe While it has been difficult, as mentioned, to find pristine LIP contexts, there is significant evidence that supports this hypothesis, in the form of several nearby LIP sites, the existence of LIP contemporary dates obtained for Co37, the presence of architecture in the local tradition, local ceramics, and the mining-metallurgical tradition of the region itself.

Lastly, some dates associated with the furnaces of Ujina sector are also consistent with a LIP occupation Table 1. Ujina has furnaces dated to the LIP, as well as other Inca ones.

metalurgia del hierro yahoo dating

At the UJ10 site, furnace 3 yielded two dates: It is interesting to see the dates of furnace 3: Cal AD corresponds rather to a phase where the metallurgical site was already controlled by the Inca administration. The version I saw also had a buffer circuit assembly on the antenna input to allow multiple receivers to use a single antenna.

Originally, the wire screen grilles were flocked with a champagne colored mohair but this seldom survives today. Since this is an approximation and is taking into account intermixed stock, the number of receivers is rounded off to about units. Civilian production started in September and continued until around July when the new models were introduced. The back of the speaker screws in place and seals the cabinet except for the bass reflex port.

After the panels were straight and dry, I had to reglue the veneer and add some patches where the veneer was missing. These wrinkles were stamped into the metal panel during manufacture. There are other minor changes in the wiring harness.

Metales - Minerales de hierro - Encuentro

If resistors need to be replaced, the purist would use vintage originals that haven't drifted in value. The next step would be going to final test. Even the earliest manual's photo of the chassis underside show that no trimmers were used on these four coils.

From the manual, go through the parts list and order the capacitors in advance. This is just for aesthetic reasons and results in a nicer looking job. This receiver did have the standard Hallicrafters serial number tag installed on the rear of the chassis with the number H, indicating late production.

The date coded bass choke disappeared about the same time as the dated coded filter choke. Also, I install the electrolytics inside the original cans. As more serial numbers are collected the picture of how Hallicrafters handled their production schedules might become clearer.

Additionally, many of the resistors can't be measured accurately while in the circuit. Photo right is of the fungicide treatment stencil which is usually located on the back of the condenser box. The bass choke is another part stamped with a date code.