diff --git a/mods/MAPGEN/mcl_geodes/init.lua b/mods/MAPGEN/mcl_geodes/init.lua
index d2debf7cd5..db79d2e5ed 100644
--- a/mods/MAPGEN/mcl_geodes/init.lua
+++ b/mods/MAPGEN/mcl_geodes/init.lua
@@ -8,7 +8,7 @@ local adjacents = {
 }
 
 local function makegeode(pos,pr)
-	local size = pr:next(2,8)
+	local size = pr:next(4,7)
 	local p1 = vector.offset(pos,-size,-size,-size)
 	local p2 = vector.offset(pos,size,size,size)
 	local nn = minetest.find_nodes_in_area(p1,p2,{"group:material_stone"})
@@ -47,21 +47,20 @@ local function makegeode(pos,pr)
 			minetest.set_node(vector.offset(v,0,1,0),{name="mcl_amethyst:amethyst_cluster",param2=1})
 		end
 	end
+	return true
 end
 
 mcl_structures.register_structure("geode",{
 	place_on = {"mcl_core:stone"},
-	spawn_by = {"air"},
-	num_spawn_by = 2,
-	fill_ratio = 0.002,
+	fill_ratio = 0.0001,
 	flags = "place_center_x, place_center_z, force_placement",
 	biomes = ocean_biomes,
-	y_max = mcl_vars.mg_overworld_max,
+	y_max = -24,
 	y_min = mcl_vars.mg_overworld_min,
 	filenames = schems,
 	y_offset = function(pr) return pr:next(-4,-2) end,
 	place_func = function(pos,def,pr)
 		local p = vector.new(pos.x + pr:next(-30,30),pos.y,pos.z + pr:next(-30,30))
-		makegeode(pos,pr)
-	end,
+		return makegeode(pos,pr)
+	end
 })
diff --git a/mods/MAPGEN/mcl_structures/API.md b/mods/MAPGEN/mcl_structures/API.md
index 52d40b642f..23d93c712a 100644
--- a/mods/MAPGEN/mcl_structures/API.md
+++ b/mods/MAPGEN/mcl_structures/API.md
@@ -1,7 +1,9 @@
 # mcl_structures
 Structure placement API for MCL2.
 
-## mcl_structures.register_structure(name,structure definition)
+## mcl_structures.register_structure(name,structure definition,nospawn)
+If nospawn is truthy the structure will not be placed by mapgen and the decoration parameters can be omitted. This is intended for secondary structures the placement of which gets triggered by the placement of other structures. It can also be used to register testing structures so they can be used with /spawnstruct.
+
 ### structure definition
 {
 	fill_ratio = OR noise = {},
@@ -14,9 +16,9 @@ Structure placement API for MCL2.
 	flags = (default: "place_center_x, place_center_z, force_placement")
 	(same as decoration def)
 	y_offset =, --can be a number or a function returning a number
-	filenames = {} OR place_func = function(pos,filename)
-	-- filenames can be a list of any schematics accepted by mcl_structures.place_schematic
-	after_place = function(pos)
+	filenames = {} OR place_func = function(pos,def,pr)
+	-- filenames can be a list of any schematics accepted by mcl_structures.place_schematic / minetest.place_schematic
+	after_place = function(pos,def,pr)
 }
 ## mcl_structures.registered_structures
 Table of the registered structure defintions indexed by name.
diff --git a/mods/MAPGEN/mcl_structures/api.lua b/mods/MAPGEN/mcl_structures/api.lua
index be86df5309..2235d44053 100644
--- a/mods/MAPGEN/mcl_structures/api.lua
+++ b/mods/MAPGEN/mcl_structures/api.lua
@@ -1,24 +1,8 @@
 mcl_structures.registered_structures = {}
 
---[[] structure def:
-{
-	fill_ratio = OR noise = {}
-	biomes =
-	y_min =
-	y_max =
-	place_on =
-	spawn_by =
-	num_spawn_by =
-	flags = (default: "place_center_x, place_center_z, force_placement")
-	(same as decoration def)
-	y_offset =
-	filenames = {} OR place_func = function(pos,filename)
-	after_place = function(pos)
-}
-]]--
-
 function mcl_structures.place_structure(pos, def, pr)
-	if not def then return end
+	if not def then	return end
+	local y_offset = 0
 	if type(def.y_offset) == "function" then
 		y_offset = def.y_offset(pr)
 	elseif def.y_offset then
@@ -28,9 +12,15 @@ function mcl_structures.place_structure(pos, def, pr)
 		local file = def.filenames[pr:next(1,#def.filenames)]
 		local pp = vector.offset(pos,0,y_offset,0)
 		mcl_structures.place_schematic(pp, file, "random", nil, true, "place_center_x,place_center_z",def.after_place,pr,{pos,def})
+		minetest.log("action","[mcl_structures] "..def.name.." placed at "..minetest.pos_to_string(pos))
+		return true
 	elseif def.place_func and def.place_func(pos,def,pr) then
-		def.after_place(pos,def,pr)
+		if not def.after_place or ( def.after_place  and def.after_place(pos,def,pr) ) then
+			minetest.log("action","[mcl_structures] "..def.name.." placed at "..minetest.pos_to_string(pos))
+			return true
+		end
 	end
+	minetest.log("warning","[mcl_structures] placing "..def.name.." failed at "..minetest.pos_to_string(pos))
 end
 
 function mcl_structures.register_structure(name,def,nospawn) --nospawn means it will be placed by another (non-nospawn) structure that contains it's structblock i.e. it will not be placed by mapgen directly