Comments to the geochemical research of Saksayhuaman artifacts

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During the georadar investigation of Saksaywaman archaeological site there was selected a number of specimento be used for further research. The samples are represented by the material of construction blocks, rock formations, processed surfaces of the “cut” rocks and other various formations which excite the curiosity in terms of their composition and origin.

The mandatory prerequisite for the selection was the integrity of the monument; the specimens were collected solely in the areas where the integrity of the construction material was already interrupted by existing cracks.
These specimens were sent for analysis into the different laboratories. The official research is, however, available only from the laboratory of the Institute of Tectonics and Geophysics of FEB RAS in Khabarovsk (where the most exhaustive set of specimens was delivered, though only 10 of them were investigated so far) and from the laboratory of the Geology of Oil and Gas faculty of the South Federal University where a fragment of a processed construction block from the archaeological site was researched.

The research continues and, therefore, at present one can only speak of the preliminary conclusions based at a limited number of the factual material.

At the map there are marked the spots of the factual sampling.
        1-7 – the specimens of the wall blocks
        8 – a specimen of a rock formation at the top of the hill
        9 – a specimen of rock with the tracks similar to the processing of a ductile material
        10 – a specimen of a rock formation from the site that is assumed to have been a stone quarry where the materials for the wall construction were extracted.

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Here it is presented the description of the mentioned specimens, as well as their cross-sectional view and the summaries prepared by the ITAG experts.

The specimens 1-3 were extracted from the blocks of walls of the first level and they have a dark-grey or almost black colour, and possess the tracks of a continuous influence of the environment (the specimens were taken from the top sections of large blocks).

Specimen 1.

The top block of the western wall.

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Cross-sectional view:

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Description: Fine-crystalline limestone with no tracks of organic residues.

Specimen 2.

The top block of the first merlon of the wall.

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Cross-sectional view:

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Description: Fine-crystalline limestone with no track of organic residues.

Specimen 3.

The top block of a section of the 9th merlon of the firs wall level.

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Cross-sectional view:

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Description: Fine-crystalline limestone with no tracks of organic residues. Intensely fissured and recrystallized.

Specimens 4-7 were obtained from the level 3 and 4 of the wall. They were taken from the internal part of the brickwork and, hence, they were less subjected to the environmental impacts. Their level of hardness is equal to 4 according to the Mohs’ scale (glass-scratchable, blunting the iron nails).

Specimen 4.

A fragment of the block from the wall which was destroyed in 2010. The fragment has a processed surface (white dots at the surface).

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Cross-sectional view:

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Description: Organogenetic limestone. Organic residues are well observed.

Specimen 5.

The block fragment from a destroyed wall of level 3. The fragment has a processed surface.

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Cross-sectional view:
 
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Description: Fine-crystalline limestone. Organic residues may be present.

Specimen 6.

The block fragment from a destroyed wall of level 3.

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Cross-sectional view:

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Description: Fine-crystalline limestone with no tracks of organic residues. It is composed of the evenly distributed calcite micro-crystals of the size of 1-10 microns. Calcite origin was confirmed by the X-ray phase analysis. Occasionally, the tiny streaks and seams are observed. These are filled with a more coarse-crystalline calcite.

Specimen 7.

The wall in the archaeological site above level 3.

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Cross-sectional view:

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Description: Fine-crystalline limestone with no tracks of organic residues.

Specimen 8.

One of outcrops of a rock formation to the hill’s surface (Muyoqmarka).

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Cross-sectional view:

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Description: Fine-crystalline limestone with no tracks of organic residues; recrystallized in fissures.

Specimen 9.

A rock in the area of Qocha. Tracks similar to processing of a ductile material are available.

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Cross-sectional view:

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Description: Fine-crystalline limestone with no tracks of organic residues, recrystallized in fissures.

Specimen 10.

A rock formation from the stone quarry.

A pre-Hispanic stone quarry is located within 1 km and at the height of 100 meters as compared to the walls of the fortress. The quarry is surrounded by the wall; assumingly, it was built after the construction of the Saksaywaman fortress. To the stone quarry from the fortress there leads a wide road– assumingly, it was built by Incas. It is deemed to be the stone quarry of Huayranga, mentioned by the chroniclers Bernabe Kobo and Polo de Ondegardo, where the stones for the construction of the Saksaywaman walls were procured. The specimens were collected for the purpose of investigation of this hypothesis.

The road and the wall around the mine:

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The stone quarry and a specimen:

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Cross-sectional view:

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Description: Organogenetic limestone with organic residues.

The roentgen-fluorescent analysis revealed a basically identical chemical composition of the specimens 10 and 6 (from a quarry and from a wall block):

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Additional research of specimen 4 with the help of electronic microscopy and microanalysis conducted at Rostov University

Specimen’s cut

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Description: Fine-grained massive limestone. Main constituent – fine-grained calcite (Са ~ 39,5%, Mg ~ 0.25%).

These contain the fine grains of quartz and potassium feldspar (usually eroded), the solitary grains of iron oxides (hydroxides?) of irregular shape and the size of 20-30 microns and the crystals of potassium chloride (KCl).
 
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Spectrum

O

Na

Mg

Al

Si

K

Ca

Ti

Fe

Total

Spectrum 1

48,96

0.04

-

9.28

28.10

13.08

(0.36)

-

0.06

99.61

Spectrum 2

49.19

0.40

0.39

17.06

19.35

8.20

(0.39)

0.45

0.66

96.10

All of these impregnations are deemed to be natural for this limestone.

Upon a special request there was performed the analysis of an unprocessed surface of the material:

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The surface is covered with certain impurities, dust and current organics (Fig. 3); particles of copper were also found (Fig. 1, 2):

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Fig. 1. Copper particle

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Fig. 2. The spectrum of copper particles

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Fig. 3. Organic material

Thermal analysis of sample 4:

Performed at the department of Geology of Oil and Gas of SFU.

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At the DTA (differential thermal analysis) curve there can be seen a specific heat endothermic effect. The peak maximum equals to 8600 C. It well corresponds to the calcite decomposition process. CaCO3 decomposes into CaO and CO2. With this its mass reduces at 42,54% that can be seen at the thermogram (TG). The DTA curve is rather typical for the natural calcite.

Preliminary conclusions

The Saksaywaman construction material is evidently represented by the organogenic and fine-grained limestone with no organic residues and with a low amount of their fragments.
ITAG experts suggest that the fine-grained limestone may be an artificial material produced with unknown technologies. This statement is presented in the official summary.
On the other hand, the experts of Fersman Mineralogical Museum in Moscow, of the Geology Department of St-Petersburg State University and of the Department of Geology of Oil and Gas of the South Federal University have expressed their opinion during the private consultations that the mentioned fine-grained limestone is deemed to be a natural formation.  


The conducted research:

Institute of Tectonics and Geophysics after Yu.A.Kosygin FEB RAS
Performed by: Deputy Director, PhD Berdnikov N.V.

Rostov University
Performed by: department research expert Gorlova Yu.V.

 

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