This was so enjoyable to do. Hand drawn using black 0.03, 0.05 and 0.1 fine liners on A4 medium cartridge paper. 22.5 hours of work and made my eyes hurt!
Freehand sketching in ink from a photo reference I found online, to practice conveying that lots-of-stones look without drawing all the stones (photo credit: K. Mitch Hodge). Micron pens + alcohol markers.