Add sandstone to sand beaches. Add skarn and peg to default:stone.

rocks/pegmatite.lua

@@ -15,7 +15,7 @@ minetest.register_node( "rocks:pegmatite", {
 
 -- pegmatites are only 1 kind
 rocks.register_vein("rocks:pegmatite",{
-  wherein={ "rocks:granite" },
+  wherein={ "rocks:granite", "default:stone" },
   miny=-160, maxy=20,
   radius={ average=18, amplitude=0.3, frequency=16 },
   density=80, rarity=CommonRarity,

rocks/sed.lua

@@ -105,6 +105,10 @@ do
    elseif def.humidity_point>70 then
     def.node_filler="rocks:laterite"
     def.depth_top=0
+   elseif def.node_top=="default:sand" then
+    if def.depth_top<2 then def.depth_top=3 end
+    def.node_filler="default:sandstone"
+    def.depth_filler=5
    end
   elseif btype=="ocean" then
    def.node_stone="rocks:basalt"

rocks/skarn.lua

@@ -4,7 +4,7 @@
 
 local CommonRarity=40 --too high... should be like 76
 local CommonRadius=10
-local CommonWherein={ "rocks:granite", "rocks:limestone" }
+local CommonWherein={ "rocks:granite", "rocks:limestone", "default:stone" }
 
 minetest.register_node( "rocks:skarn", {  
 	description = S("Skarn"),