Stone : siltite (almost transformed into a slate)
Type : metamorphic rock derived from a sedimentary rock
Age : between 590 and 540 million years
Carrière : Ripennelais, Saint-Aubin des Landes (Ille-et-Vilaine)

Rustic Slates

This rock has been exploited for over two centuries, initially used to make lauzes, those rustic, thick slates used on roofs in certain regions of France. However, due to its poor slate quality, this rock—over 500 million years old—was no longer in demand, and slate production had to be abandoned by the end of the 1990s.

A Friend Against the Rain

Since it was easier to crush the material into small pieces than to extract slates, by the 1960s, the company diversified its production and specialized in producing flakes to utilize quarry waste. These flakes were then used in the manufacture of bituminous shingles (shingle in English). They protect tar from solar and lunar radiation and remain effective allies for rain protection.

The Age of Mulching

In the 2000s, the family company ventured into "mineral mulching" for the landscaping sector. This mulch, complementary to plant-based mulching, has numerous advantages: it retains soil heat, provides shelter for wildlife, remains permeable to water and air, and helps limit weed growth.

Made with… Brilliance

This siltstone belongs to a geological formation dated to the Briovérien period, a geological time frame between 670 and 540 million years ago. The term "Briovérien" comes from the Latin briovera, meaning "bridge over the Vire," which is the former name of the town of Saint-Lô in Normandy, where this geological formation also outcrops.