Columbretes

“The other islands—La Foradada, La Ferrera, Bauzá and El Bergantín—provide trachytic materials of two somewhat different types.

One is similar to the type of sanidine trachyte found on La Foradada and El Bergantín in the hard, light grey-coloured rocks that interweave with brilliant white crystals. The other, characterised by a dark colour and higher hornblende content, is similar to what is known as Arso (from the Arso flow on the island of Ischia).

Many of the rocks on La Foradada are of this type. They are often characterised by a flaky texture and red and black colour. Black is the original colour, whereas the red appears to be an alteration that occurred during the eruption. It is mainly found in places where the rock is porous and spongy, due to the vapours that were generated.”

Urios, G., Nachtwey, J., Translation, Columbretes, 1895, Castellón City Council, 1990.