Click the images

The slate from Valongo is well known due to the specific characteristics of the area where it is found (Valongo - Douro Litoral) and due to the geological age of its mines (Upper Landeilian).

Click the images

Slates are rocks which are easily split into thin sheets along a plane of cleavage resulting from a schistosity flux, caused by very low or low grade metamorphism due to tectonic compression.

Click the images

The slates originate from sedimentary clay rocks and belong petrographically to a range which begins at the boundary between sedimentary and metamorphic formations and ends at the epizonal-metamorphic phyllite formations.

Click the images

Micaceous and occasionally also chlorotic minerals are the predominant and most important components. These are mixed with fine-grain quartz and a larger or smaller quantity of clay minerals, depending on the degree of metamorphosis in each case.
 

More applications