black volcanic rocks with salt residues due to evaporation of sea water, salt and saltpetre on black lava rocks

salt lava rocks saltpetre black volcanic evaporation residues saline seawater texture abstract nature ock mineral geology natural rugged erosion landscape sea water formation rough outdoors stones solid crust surface coastline sediment harsh terrain coastal island ocean minerals dry cracked weathered barren earth seaside rock structure coarse roughness resilience white