In November of 2016 I took part in an interview for the Allegorithmic Blog which also included a detailed breakdown of my Rock Substance I had created earlier in the year.
The full interview and breakdown is available to read at https://www.allegorithmic.com/blog/chris-hodgson-one-substance
The original Rock Substance featured in the breakdown can be seen here at https://www.artstation.com/artwork/xmmNW
If you would like to have access to the full .sbs source file you can purchase it along with a lot of other high quality substance materials in my Substance Material Collection on my Gumroad page at https://gumroad.com/l/yKuIQ
If you have any questions regarding the breakdown and my methods don't hesitate to ask them here on ArtStation in the comments.