H.S.G.M.E. studies the building materials of the historic underground settlement of **Agrilia** as part of the program “Under the Landscape: Thirasia 2021–2022.”

The Hellenic Survey of Geology and Mineral Exploration (H.S.G.M.E.) is participating in the program “Under the Landscape: Thirasia 2021–2022”, conducting research on the building materials of the historic underground houses of Agrilia, one of the most significant traditional settlements in Greece.

Petrologist Dr. Christos Papatrechas is examining mortar and plaster samples from the subterranean settlement under a polarizing microscope at the “LITHOS” Laboratory of the H.S.G.M.E. The results of the petrographic–mineralogical study reveal for the first time the construction materials from the natural environment that were used to build these underground houses, notable for their unique architecture, functionality, and harmony with the surrounding landscape.

The aggregates observed consist mainly of pumice fragments, volcanic rocks, and crystalline fragments of quartz, plagioclase, pyroxenes, etc., while the binding material is composed of very fine-grained calcite and small fragments of pumice and crystals.

The project is co-organized by “Mpolouki – Travelling Workshop for Traditional Building Techniques”, the Municipality of Thira, and the Community of Thirasia. From May 28 to 30, 2021, the program’s inaugural event, “Meeting Under the Landscape,” took place — a three-day collaborative workshop during which the team, students and teachers of the Thirasia school, students and instructors from the Athens School of Fine Arts (A.S.F.A.), and other participants from Thirasia and Thira cleaned the main path of the underground settlement of Agrilia.

It is noted that the program “Under the Landscape: Thirasia 2021–22” is under the auspices of the Hellenic National Commission for UNESCO and the Technical Chamber of Greece (T.E.E.). It is carried out in collaboration with the Ephorate of Antiquities of the Cyclades (EFA Cyclades), the Laboratory of Building Materials of the National Technical University of Athens (NTUA), the “LITHOS” Laboratory of the H.S.G.M.E., the A.S.F.A., and the Department of Architecture at ETH Zürich, with the support of the J.M. Kaplan Fund. More information is available on the program’s official website: https://el.underthelandscape.net/

Below are photographs from the research of Dr. Christos Papatrechas at the “LITHOS” Laboratory of the H.S.G.M.E.:

Dr. Christos Papatrechas conducting petrographic–mineralogical analysis of the building materials from Agrilia, Thirasia.

Polarizing microscope image (Nicols X, x200): the binding material of the aggregates is composed of calcitic material. The observed aggregate is a pyroxene crystal approximately 150 μm in size.

Polarizing microscope image (Nicols X, x200): the binding material of the aggregates is composed of calcitic material. The observed aggregate is a pyroxene crystal approximately 150 μm in size.

Sample of pumice concrete (macroscopic image)