Theese files were copied from minetest decoblocks mod. Original files were 
in "default/textures" and with "default_" prefix instead of "rocks_".

rocks_bb.png
rocks_blkgr.png
rocks_brgr.png
rocks_gls.png
rocks_mrbrownstone.png
rocks_obs.png
rocks_pgr.png
rocks_rss.png
rocks_serp.png
rocks_sod.png
rocks_trav.png
rocks_wgr.png
rocks_wm.png
rocks_yss.png