Chemical Analysis of Floors in La Casa de las Aguilas, Templo Mayor, Using NITON pXRF and Spot Tests Claudia Brackett, Richard Lundin, Luis Barba, Agustin Ortiz, and Martin Terreros

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The study site is located in the Aztec City of Tenochtitlan and is presently in downtown Mexico City

The study site, The House of the Eagles, is located to the north of Templo Mayor

Samples were collected with a masonry drill. Samples were bagged and taken to the laboratory for analysis.

The samples were treated to chemical spot tests for protein, carbohydrates, fatty acids, pH, and phosphorous The samples were treated to chemical spot tests for protein, carbohydrates, fatty acids, pH, and phosphorous.

Then the samples were analyzed for up to 22 elements by portable X-ray fluorescence

Do not try to read all this data. Just understand the wealth of information that we had to choose from. 22 elements times all of the sample sites gave us a lot to work with.

We decided to focus attention on elements that complemented the results of the chemical spot tests

First, the raw numbers were graphed so that trends could be determined. Relevant elements were selected for further analysis and mapping.

This is the floor plan for the House of the Eagles. Numbers indicate sample locations. The chemical spot tests were done for all of these samples.

pXRF analysis of the elements was done only for samples taken from the inner room.

The pXRF data will be displayed on this schematic of the inner room.

Statuary was found at the site. Their locations are indicated here.

The results of the chemical tests suggested use areas

High pH (dark red) is associated with ash.

Here ashes are associated with the braziers. High values are in portico area, while the lower values are in the central room. Higher pH values occur in areas surrounding the main altar. The highest values are around the braziers in the north doorway and the corners of the pillars. X X X X

Potassium, (K), is also associated with wood fires. The pXRF distribution in the inner room indicated a fairly even distribution of K

Potassium distribution is reasonably consistent with pH thus supporting the assignment of ash.

Phosphorous can be an indication of organic tissue deposition. Phosphorous enrichment has been associated with food preparation and burials. Possible sources of phosphorous are nucleic acid and the phospho-lipid cell membrane. Phosphorous could also be expected from blood deposition.

High levels of phosphorous were in the portico while low values were in the open patio. Important concentrations can be observed close to the altars and braziers. Phosphorous values increase in the doorways between the sculptures.

Protein, specifically albumin was assayed. Protein suggests the presence of blood.

The highest values of protein were in the portico while the inner rooms were clean.

Protein was present where Mictlantecuhtli with flesh statues were placed on both sides of the north doorway

This can be explained by the reported practice of pouring blood on the sculpture’s head

Protein was also present in the middle of the doorway where eagle-dressed men figures were placed. Also, high concentrations of protein were found in front of the skeletal Mictlantecuhtli suggesting a self sacrifice

Iron from hemoglobin would be associated with blood. It could also be a pigment used in wall decorations

The pXRF analyzed distribution of iron showed definite activity areas

To further confirm the presence of blood deposition, we would like all of the chemical evidence to be consistent. Blood contains albumin protein, iron from hemoglobin, and phosphorous from cell membranes. If the concentration patterns coincide it further corroborates the presence of blood.

It was found that the concentration patterns of protein, iron, and phosphorus did correspond in two areas of the room. This is shown on the next slide.

Phosphorous IronProtein

The results of phosphorous, iron and protein chemistry all indicate the deposition of blood.

Iron could also be explained as coming from paint or decorative pigments. In this case we wanted to establish a negative coorelation between iron and copper.

Copper is an important ingredient for certain blue and green pigments. Its distribution could indicate decorative features. Copper was plotted to contrast with iron distribution.

Copper distribution is concentrated near walls

Copper distribution patterns are dissimilar to iron except along one wall.

Fatty acids are associated with animal fats and tissue. Such fatty acids could be deposited around braziers where offerings were burnt. Fatty acids can also be found in the tree resins used to make copal. Copal was most frequently burnt as an incense, but could also be used as a paint binder. Fatty acids can also be found in the tree resins used to make copal. Copal was most frequently burnt as an incense, but could also be used as a paint binder.

Fatty acid depositions were found near braziers and in front of altars.

Gas Chromatography has identified high molecular weight fatty acids that suggests copal resins in front of the main altar.

Conclusions Chemical analysis was useful in determining different activity areas of the House of the Eagles. Examples are as follows.

Conclusions The location of braziers and ritual fires.The location of braziers and ritual fires. The use of copal at the main altar.The use of copal at the main altar. The pouring of blood on the Mictlantecuhtli with flesh sculpture, but not the other sculptures.The pouring of blood on the Mictlantecuhtli with flesh sculpture, but not the other sculptures. The practice of self sacrifice near the inner door sculptures.The practice of self sacrifice near the inner door sculptures.

Thanks To Thermo Fisher Scientific NITON Analyzers.Thermo Fisher Scientific NITON Analyzers. Universidad Nacional Autónoma de México (UNAM)Universidad Nacional Autónoma de México (UNAM) California State University StanislausCalifornia State University Stanislaus