Esterellite

Small block of Esterellite taken on a beach between Saint-Raphaël and Le Dramont

Esterellite (or Estérellite) is a porphyritic variety of quartz-bearing microdiorite, containing phenocrysts of quartz, zoned andesine, and hornblende only found in the southern part of the Esterel massif, between Agay and Saint-Raphael, France.[1] It is a bluish-grey rock, sometimes greenish, dotted with white plagioclase feldspar and amphibiole crystals, forming a thick laccolithic complex near Le Drammont.

This volcanic rock, also known as the blue porphyry of Estérel, was named by the French geologist Auguste Michel-Levy in 1896.[2][3] The Romans used it as paving materials but also for decorative purposes. Today, it is mainly used to make riprap, such as blocks for the dykes of the ports of Saint-Raphaël and Fréjus, railway ballast and road gravel.

  1. ^ Holmes, Arthur (1920). The nomenclature of petrology, with references to selected literature. University of California Libraries. London, Thomas Murby & co. p. 94.
  2. ^ Michel-Lévy, Auguste (1896). "Sur quelques particularités de gisement du porphyre bleu de l'Esterel". Bulletin de la Société géologique de France. 3. 24. Paris: Société géologique de France.: 123–139. Archived from the original on 2024-07-31. Retrieved 2024-07-31.
  3. ^ Michel-Lévy, Auguste (1897). Mémoire sur le porphyre bleu de l'Estérel (in French). Archived from the original on 2024-07-31. Retrieved 2024-07-31.