![]() ![]() Sintubin & Everaerts (2002) think that this gravity anomaly is due to the presence of a granitic Precambrian crustal block. Feldspar phenocrystals can be seen, partially replaced by chlorite in a recrystallised microcrystalline matrix (thin flake, crossed nicols). Quartziferous microdiorite (Quenast porphyry), Brabant formation. An as yet unanswered question is the relationship between the intrusive rocks and the various Bouguer anomalies shown by the geophysics between the south of the East Flanders province and Wavre in Wallony Brabant (Mansy et al, 1999). This calc-alkaline volcanism continues to Llandovery to the east of Brabant and in the Condroz Caledonian inlier. © DRĪt Quenast, The 2 km diameter vertical subcircular intrusion is composed of a 433 million year old quartziferous hornblend diorite (André & amp Deutsch, 1984). Quenast " porphyry" quarry, Brabant formation. ![]() One of the two centres of emission is located to the south of Brussels at Lessines and Quenast. After the collision between Avalonia and Baltica and the closure of the Tornquist ocean, the occurrence of these intrusions is probably associated with the subduction of a small oceanic crust between the two Avalonia blocks (Verniers 2002). Here are 2 examples of regions where porphyry is extracted.įrom the end of the Ordovician to the beginning of the Silurian, a volcanic arc developed in the southern part of the Brabant formation extending under Flanders. It is also used as decorative stone when polished (floor tiles, walls etc.), especially green and black porphyry. Porphyry no longer has the noble character of the past and is now used for paving as it is a strong resistant stone. The stars thus create a link between Man and agrarian and cosmic phenomena. 8 th circle : this is the circle of the Milky Way.For the Mexicans, Tezcatlipoca, the Black Mirror, is deeply connected to Tecciztecatl, the Moon. 6 th circle : this corresponds to the planet Jupiter.5 th circle : this is linked to the planet Mars.4 th circle : this is formed by the 8 rays of the Sun and shows the relationship between the Sun and Venus.The civil year was composed of 18 months of 20 days. 3 rd circle : this is composed of the 20 days of the month and rotates in the same way as the previous one. ![]() The 4 blades show the 4 days that open the year: Acatl, Tecpatl, Calli, Tochtli. 2 nd circle : the arms of the cross linked to the 4 elements.His tongue, shown as an obsidian knife, symbolises his own sacrifice, source of vitality and creation. The central circle, represented by the face of the Sun Ollin Tonatiuh and his two claws which seized hearts to fix himself to the Universe, the symbol of vitality.The 8 concentric circles on this stone are split as follows. It was not only in Europe that this very hard stone was used for precious and " eternal " objects, as this 3.6 m diameter round Aztec stone (below) shows. Napoleon's tomb is not in porphyry but in quartzite, but Alexander's bust (photo below) is porphyry ! The Sun Stone The discovery of porphyry deposits, first in Sweden, then elsewhere in Europe, made this stone common. In Rome, at the Seicento, sculptors exported porphyry vases to the whole of Europe, a thriving industry that declined up to the end of the 18 th century. The difficulty of carving makes sculptures in this material rather unsophisticated. Up to the end of the 18 th century the objects were made by recycling antique objects, which were either re-carved to make new works or reused with other materials ( marble, serpentine, bronze etc.). Their location has more or less been forgotten. Porphyry quickly became rare and Egyptian deposits from the time of Ptolemy are no longer worked. Objects in porphyry are found in the Middle Ages, even if a legend propagated Vasari claimed that the secret of its sculpting was re-discovered in the 16 th century in Florence. © National museum of the châteaux of Versailles and the Trianon The hardness of porphyry makes it difficult to work, and is at the origin of its mythical character and of its colour too, associated with the imperial colour purple and sometimes with the blood of the Eucharist.Īlexander the Great. © DR Porphyry: the purple stone of the emperors It now refers more to the texture of rocks. It is now a commercial name and is no longer officially used in petrology. with no distinct crystals visible to the naked eye). The name of porphyry is given to any igneous rock containing large feldspar crystals dispersed in an aphanitic matrix (i.e. ![]()
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