Mont Aiveu
The place is quite unique because there is no car noise, the sandstone is of excellent quality (sometimes pink) and there are a few limestone pebbles. On the IGN map it is point 117. Above 100m altitude there is sometimes limestone.
From the D148 (parking 1): exactly 1200m. There are four path intersections with the Route de la Garenne du Gros Bois. At the fourth path on the left (no name indicated), take a small path on the right which goes up slightly towards the north-west. The boulder quickly becomes visible (around 200m).
From D58 (parking 2): exactly 1500m. There are five path intersections with the Route de la Garenne de Gros Bois. At the fifth path on the right (no name indicated), take a small path on the left which goes slightly uphill towards the north-west. The boulder quickly becomes visible (around 200m).