Add minerals to giant trees. Raise fortresses to -33 max.

This could cause issues with really deep oceans, but I haven't seen any.

treegen.lua

@@ -15,6 +15,44 @@ newnode.tiles = {"fun_caves_tree.png"}
 newnode.is_ground_content = false
 minetest.register_node("fun_caves:tree", newnode)
 
+newnode = fun_caves.clone_node("fun_caves:tree")
+newnode.description = "Giant Wood With Mineral"
+newnode.tiles = {"fun_caves_tree.png^fun_caves_mineral_aquamarine.png"}
+-- This drop list is more complicated than it ought to be.
+-- The lua documentation is inaccurate.
+newnode.drop = {
+	max_items = 1,
+	items = {
+		{
+			items = { 'fun_caves:aquamarine', },
+			rarity = 10,
+		},
+		{
+			items = { 'fun_caves:moonstone', },
+			rarity = 10,
+		},
+		{
+			items = { 'fun_caves:garnet', },
+			rarity = 10,
+		},
+		{
+			items = { 'fun_caves:zoisite', },
+			rarity = 10,
+		},
+		{
+			items = { 'fun_caves:coral_gem', },
+			rarity = 30,
+		},
+		{
+			items = {
+				'fun_caves:meteorite',
+			},
+			rarity = 1,
+		},
+	},
+}
+minetest.register_node("fun_caves:tree_mineral", newnode)
+
 minetest.register_craft({
 	output = 'default:wood 4',
 	recipe = {
@@ -268,8 +306,12 @@ fun_caves.treegen = function(minp, maxp, data, p2data, area, node)
 						data[ivm] = node['fun_caves:diamondwood']
 					end
 
-					if data[ivm] ~= node['air'] and data[ivm] ~= node['fun_caves:weightless_water'] and math_random(500) == 1 then
-						data[ivm] = node['fun_caves:sap']
+					if data[ivm] ~= node['air'] and data[ivm] ~= node['fun_caves:weightless_water'] then
+						if math_random(500) == 1 then
+							data[ivm] = node['fun_caves:sap']
+						elseif math_random(1000) == 1 then
+							data[ivm] = node['fun_caves:tree_mineral']
+						end
 					end
 					write = true
 				elseif y < 222 and y > -132 and distance < r + 2 then