Observe the rock’s overall shape
Sketch a simple base form
Add angular edges or rounded contours
Mark major planes and surface breaks
Indicate cracks, chips, and crevices
Refine the silhouette
Add smaller irregular details
Place light and shadow areas
Shade along the planes and folds
Use varied line weight for depth
Blend or crosshatch to suggest texture
Darken crevices and undersides
Keep edges uneven and natural
Compare proportions and adjust as needed