The displacement function I used can be divided into 3 elements.

1-  Simple fractal/ Noise: Cellular pattern/voronoi 1st-2nd neighbors/spikes followed by filters (as Monsoon suggested). The noise has been chosen to create cracks.

2- Simple fractal/ Noise:Cellular pattern/Crystals. This function should add sharpness.

3- Simple fractal/ Experimented with various noises, mainly Gradient Perlin Noise and Terrain Perlin Noise. This noise is converted into a vector and feeds the origin of the two fractal nodes below. The effect is what can be achieved with turbulence noise. However with the way I chose, the unconverted noise can be mixed with the two other fractal nodes.

The left part is for coloring

4- Color is very simple. The left node is a Color Variation Map.
To the right is a Color Map node into which the "cracks" are fed, in order to apply a darker color to them.

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