Historical & Geological Context
Extracted from the deep subterranean schist veins of Trélazé near Angers, this world-renowned blue-black slate (schiste ardoisier) has roofed the Loire châteaux and Paris monuments for five centuries. Hand-split with chisel and mallet (fendoir), its pyritic stability, non-fading colour, and longevity exceeding two centuries make it the pinnacle of French roofing craftsmanship.
Petrographic & Geological Characteristics
Silurian-Ordovician clay schist split manually along cleavage planes into thin roofing slates.
Lime Mortar & Breathability Compatibility
Fixed with copper nails or pure lime torching (lait de chaux) under the lap for wind protection.
Provenance & Historical Sourcing
Anjou geological schist formations.
Condition Report & Patina
Selected hand-split quality; zero carbonate or oxidizable pyrite inclusion.
Ardoise Naturelle d'Angers-Trélazé Clivée Main
Anjou, France (FR)
Non-commercial reference. Not sold or brokered by Le Cercle du Roi.
This material dossier is compiled from public geological surveys, heritage conservation research (BRGM, CTMNC, Historic England, Monumentenwacht), and historical treatises. Inclusion does not constitute a sales offer by Le Cercle du Roi.