Gerolekas Bauxite Exploration Site, Greece Bauxite ore is the most abundant rock found in the Earth’s crust, although bauxite refers to any material that contains >32% alumina. There are three main types of bauxite but the low water content varieties, böhmite and diaspore (monohydrate) comprise typical deposits in Greece. The exploitation of bauxite is an important part of the mineral wealth of Greece and an important source of raw materials for Europe. Exploitable bauxite deposits are located in the mountainous regions of Parnassos, Giona and Helikon (Central Greece) and estimated at 100 Mt. Economically significant bauxite occurrences are reported at Kallidromon, Iti, Othrios, Evia, Skopelos and Eleusis. The mineralogical composition of bauxites in the Parnassos-Giona region is:

• Diaspore, 20 – 50%
• Böhmite, 10 – 30%
• Hematite, 20 – 25%
• Calcite, 1 -5%
• Kaolinite, 1-5%

The exploitation of bauxite ore found in Greece bears an important mining tradition dating from the early 1930’s with current reserves estimated at 600 Mt (2% of global total). Delphi-Distomon, a subsidiary of Aluminium of Greece is one of the largest bauxite producers in Europe and is interested to start exploration for new deposits. The exploration area (~25km²) to be investigated, Gerolekas, the (highest) nappe of Western Thesally – Boetia, lies with a sub-horizontal contact above the Parnassos thrust sheets at the western end of the Parnassos Mountain. The topographic difference between the footwall carbonates of Parnassos and the nappe of Western Thessaly-Boetia in Gerolekas at the hangwall is 900 – 1,000m.  Currently there is no geological information available below the depth of 400m on the continuation of bauxite deposits. Bauxite deposits in Greece are primarily hosted within a carbonate sequence forming part of the Mediterranean karst bauxite belt. These deposits are, mainly found within the Parnassus-Ghiona geotechnical zone, in the mountain region of Parnassus, Helikon and Giona. Bauxite horizons were deposited in the underlying irregularly shaped karstic limestone formation with a pocket-like, lenticular form which is interrupted by faults at depths varying from 70m to 400m. The deposits are considered to be allochthonous forming a product of the laterisation of ophiolites in eastern Greece which were transported and deposited into karstic cavities of the underlying limestone in the Parnassus region. The deposition process occurred during three different events resulting in three distinct bauxite horizons formed during the Jurassic and Cretaceous periods. Only the uppermost two bauxite horizons host economic deposits and the uppermost unit is most significant with diasporic bauxite. *Karstic bauxite – partially transformed or transformed bauxite material washed and accumulated in eroded limestone cavities where transformation occurs.