This caramel-brown type of rock that the striped biomes of Canyons are made of is the rarest type of canyonstones and can only be found rather high up.
Stone Mining Cells are needed to mine this rock.
Mining/taking Canyonstone for the first time will automatically unlock the crafting-recipe for Stucco Wall which will then unlock many more Canyon-related recipes when being crafted/taken.
Canyonstone is necessary for crafting Stucco Walls, Copper Roofs, Copper Walls and Stucco Windows. Additionally to that, Canyonstone can be used in other recipes that will accept different kinds of canyonstones, like Wood Gravel Wall, Barred Wood Window, Cobblestone or Mossy Cobblestone.
When Canyonstones are placed as they are, Dustevils can spawn on or near them during the (ingame-)day, also - more rarely - Trogs, ordinary Leafies or even Dried Leafis, and Night Leafies during the night.
Wood Treasure Chests might also spawn on this surface-block randomy during the night in complete darkness, no matter where these blocks have been placed (as of R26 in December 2015).