Project Part 05: Database for SiO2-rocks
Head: A.o. Univ.-Prof. Dr. Walter Leitner Staff: Thomas Bachnetzer Bakk. phil. University of Innsbruck |
|
Raw material exploration is a rather young discipline in archaeological context. Mineralogical, micropalaeontological and archaeological methods of determination are combined in that field of research. In order to get a correct determination of SiO2 – rocks some simple chemical - mechanic tests can be carried out as well as geochemical ones.
The simple methods are the H2O – moistening, the HC – test and the scratching – test with a steel needle. The H2O – moistening allows a view into the structure beneath the surface of a stone, especially if it is an SiO2 – rock. This method is useful to detect inclusions of fossiles and sepecific rock elements. Using the HC – test, the extent of lathering allows to determine the amount of carbonate an SiO2 – rock contains. The scratching - test finally shows the hardness of an object. A steel needle has a degree of 6 after Mohs, therefore it is not possible to leave a scratch on SiO2, which is harder, but to scratch a softer type of rock. Put together, an examination under the microscope in combination with the described methods of analysis is a good foundation to start a clear mineralogical and micropalaeontologic description of every raw material.
Additional to this four methods of geochemical analysis look promising in first small test series: The SEM EDX (Raster – Electron – Microscope), Raman – spectroscopy, X – ray diffractometry and finally the LA-ICP-MS (Laser Ablation). All these methods are used to analyse the contained trace elements of a certain raw material sample. Combining them gives a broad – band investigation on different levels and order in analysed elements of such a sample.
Once a certain amount of determined raw material varieties are known it is necessary to systematize the results of the research. The best way to deal with that kind of data is a Database with mineralogical description and microphotos for the micropalaeontology as it is used in modern raw material analysis. The localisation and recording of the most significant raw material sources in such a Database form the basis of continuing work on that field of research.
In the course of surveys and excavations carried out by the members of project part 05 of the SFB HiMAT such a database for western Austria and adjacent areas was established and is to be continuously extended.
