rock dust (#8741)

code/modules/mining/mine_turfs.dm

@@ -391,6 +391,17 @@ var/list/mineral_can_smooth_with = list(
 			DropMineral()
 
 	//Add some rubble, you did just clear out a big chunk of rock.
+
+	if(prob(25))
+		var/datum/reagents/R = new/datum/reagents(20)
+		R.my_atom = src
+		R.add_reagent("stone_dust",20)
+		var/datum/effect/effect/system/smoke_spread/chem/S = new("stone_dust")
+		S.show_log = 0
+		S.set_up(R, 10, 0, src, 40)
+		S.start()
+		qdel(R)
+
 	ChangeTurf(mined_turf)
 
 	if(rand(1,500) == 1)