diff --git a/OpenRA.Game/Ore.cs b/OpenRA.Game/Ore.cs
index b7e2fb0942..bf8b25f807 100644
--- a/OpenRA.Game/Ore.cs
+++ b/OpenRA.Game/Ore.cs
@@ -26,43 +26,6 @@ namespace OpenRA
 {
 	public static class Ore
 	{
-		public static void SpreadOre(this World world, Random r, float chance)
-		{
-			var map = world.Map;
-
-			var mini = map.XOffset; var maxi = map.XOffset + map.Width;
-			var minj = map.YOffset; var maxj = map.YOffset + map.Height;
-
-			/* phase 1: grow into neighboring regions */
-			var newOverlay = new byte[128, 128];
-			for (int j = minj; j < maxj; j++)
-				for (int i = mini; i < maxi; i++)
-				{
-					newOverlay[i, j] = 0xff;
-					if (!map.HasOverlay(i, j)
-						&& r.NextDouble() < chance
-						&& map.GetOreDensity(i, j) > 0
-						&& world.IsCellBuildable(new int2(i,j), UnitMovementType.Wheel))
-						newOverlay[i, j] = ChooseOre();
-				}
-
-			for (int j = minj; j < maxj; j++)
-				for (int i = mini; i < maxi; i++)
-					if (newOverlay[i, j] != 0xff)
-						map.MapTiles[i, j].overlay = newOverlay[i, j];
-		}
-
-		static byte GetOreDensity(this Map map, int i, int j)
-		{
-			int sum = 0;
-			for (var u = -1; u < 2; u++)
-				for (var v = -1; v < 2; v++)
-					if (map.ContainsOre(i + u, j + v))
-						++sum;
-			sum = (sum * 4 + 2) / 3;
-			return (byte)sum;
-		}
-
 		static bool HasOverlay(this Map map, int i, int j)
 		{
 			return map.MapTiles[i, j].overlay < overlayIsOre.Length;
@@ -83,13 +46,6 @@ namespace OpenRA
 			return map.ContainsGem(p.X, p.Y) || map.ContainsOre(p.X, p.Y);
 		}
 
-		static byte ore = 5;
-		static byte ChooseOre()
-		{
-			if (++ore > 8) ore = 5;
-			return ore;
-		}
-
 		static bool[] overlayIsOre =
 			{
 				false, false, false, false, false,
diff --git a/OpenRA.Game/Traits/World/OreGrowth.cs b/OpenRA.Game/Traits/World/OreGrowth.cs
index 9b30291083..8a4e464102 100644
--- a/OpenRA.Game/Traits/World/OreGrowth.cs
+++ b/OpenRA.Game/Traits/World/OreGrowth.cs
@@ -49,9 +49,8 @@ namespace OpenRA.Traits
 				if (oreResource != null)
 				{
 					if (info.Spreads)
-						Ore.SpreadOre(self.World,
-							self.World.SharedRandom,
-							info.Chance);
+						self.World.WorldActor.traits.Get<ResourceLayer>().Spread(oreResource,
+							self.World.SharedRandom, info.Chance);
 
 					if (info.Grows)
 						self.World.WorldActor.traits.Get<ResourceLayer>().Grow(oreResource);
diff --git a/OpenRA.Game/Traits/World/ResourceLayer.cs b/OpenRA.Game/Traits/World/ResourceLayer.cs
index 6049fbb46b..69a1b31ea4 100644
--- a/OpenRA.Game/Traits/World/ResourceLayer.cs
+++ b/OpenRA.Game/Traits/World/ResourceLayer.cs
@@ -159,6 +159,32 @@ namespace OpenRA.Traits
 						++content[i, j].density;
 		}
 
+		public void Spread(ResourceTypeInfo info, Random r, float chance)
+		{
+			var map = w.Map;
+
+			var mini = map.XOffset; var maxi = map.XOffset + map.Width;
+			var minj = map.YOffset; var maxj = map.YOffset + map.Height;
+
+			var growMask = new bool[128, 128];
+			for (int j = minj; j < maxj; j++)
+				for (int i = mini; i < maxi; i++)
+					if (content[i,j].type == null
+						&& r.NextDouble() < chance
+						&& GetAdjacentCellsWith(info, i,j ) > 0
+						&& w.IsCellBuildable(new int2(i, j), UnitMovementType.Wheel))
+						growMask[i, j] = true;
+
+			for (int j = minj; j < maxj; j++)
+				for (int i = mini; i < maxi; i++)
+					if (growMask[i, j])
+					{
+						content[i, j].type = info;
+						content[i, j].image = ChooseContent(info);
+						content[i, j].density = 0;
+					}
+		}
+
 		public struct CellContents
 		{
 			public ResourceTypeInfo type;