THERE ARE SEVERAL VARIETIES OF PORPHYRY. THE ROCK EXTRACTED AT DRAMONT IS BLUE PORPHYRY, CALLED ESTERELLITE. IT HAS BEEN EXPLOITED SINCE ROMAN TIMES. THE OLD QUARRY WALLS WHICH YOU CAN STILL SEE ARE MADE OF PORPHYRY.

We call porphyry any igneous rock that presents in its structure scattered large crystals in an aphanitic paste (without visible crystals).

Esterellite is a porphyritic rock, entirely crystallized, quite clear, whitish and bluish, sometimes greenish, dotted with white crystals of plagioclase.

Its origin comes from a little hot magma, under weak pressure, which could not reach the surface and created in depth a magmatic camber, flattened in shape. Erosion of the overlying layers exposed these cooled rocks.

Esterellite is a very solid rock, for a long time used in the form of pavers or gravel because it does not did not break under the rimmed wheels of the carts. Several old properties are delimited by low walls in porphyry.

It continues to be exploited in the Caous quarry.