diff --git a/rocks/init.lua b/rocks/init.lua
index 07033d4..d476131 100644
--- a/rocks/init.lua
+++ b/rocks/init.lua
@@ -31,13 +31,15 @@ dofile(modpath.."/skarn.lua")
 dofile(modpath.."/pegmatite.lua")
 dofile(modpath.."/gensed.lua")
 dofile(modpath.."/pipes.lua")
+dofile(modpath.."/veins.lua")
 
 minetest.register_on_generated(function(minp,maxp,seed)
  local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
  local area = VoxelArea:new{MinEdge=emin, MaxEdge=emax}
  rocksl.gensed(minp,maxp,seed,vm,area)
  --rocksl.genign
- rocksl.genpipe(minp,maxp,seed,vm,area)
+ --rocksl.genpipe(minp,maxp,seed,vm,area)
+ rocksl.genvein(minp,maxp,seed,vm,area)
  vm:write_to_map(data)
 end)
 
diff --git a/rocks/veins.lua b/rocks/veins.lua
new file mode 100644
index 0000000..554d488
--- /dev/null
+++ b/rocks/veins.lua
@@ -0,0 +1,61 @@
+-- experimental fast vein generator
+
+local pr
+
+local function draw_sphere(data,area,pos,radius,with)
+ local rsq=radius^2
+ radius=radius+2
+ for x=-radius, radius do
+ for y=-radius, radius do
+ for z=-radius, radius do
+  if (x^2)+(y^2)+(z^2)<=rsq then
+   data[area:index(x+pos.x,y+pos.y,z+pos.z)]=with
+  end
+ end end end
+end
+
+local function line(data,area,A,B,with)
+ local length=vector.distance(A,B)
+ local step=1/length
+ for t=0, 1, step do
+   local p=vector.add(vector.multiply(A,(1-t)), vector.multiply(B,t) )
+   p=vector.round(p)
+   data[area:index(p.x,p.y,p.z)]=with
+ end
+end
+
+rocksl.genvein=function(minp,maxp,seed,vm,area)
+ local t1 = os.clock()
+ local data = vm:get_data()
+
+ local chunksizer = maxp.x - minp.x + 1
+ local chunksize = chunksizer + 1
+ local pmapsize = {x = chunksize, y = chunksize, z = chunksize}
+ local minpxz = {x = minp.x, y = minp.z}
+ pr=pr or PseudoRandom(seed)
+ local c_sample=minetest.get_content_id("default:mese")
+ 
+ print("pr="..pr:next().." seed="..seed)
+ print("minp="..minp.x..","..minp.y..","..minp.z)
+ print("maxp="..maxp.x..","..maxp.y..","..maxp.z)
+
+  local pointA=vector.new(pr:next(0,chunksizer)+minp.x,pr:next(0,chunksizer)+minp.y,pr:next(0,chunksizer)+minp.z)
+  local pointB=vector.new(pr:next(0,chunksizer)+minp.x,pr:next(0,chunksizer)+minp.y,pr:next(0,chunksizer)+minp.z)
+  local pointC=vector.new(pr:next(0,chunksizer)+minp.x,pr:next(0,chunksizer)+minp.y,pr:next(0,chunksizer)+minp.z)
+  local pointB2=vector.new(pr:next(0,chunksizer)+minp.x,pr:next(0,chunksizer)+minp.y,pr:next(0,chunksizer)+minp.z)
+  local step=1.3/(vector.distance(pointA,pointB)+vector.distance(pointB,pointC))
+  for t=0, 1, step do
+   local p=vector.multiply(pointA,(1-t)^2)
+   p=vector.add(p, vector.multiply(pointB,2*t*(1-t)) )
+   p=vector.add(p, vector.multiply(pointC,t*t) )
+   local p2=vector.multiply(pointA,(1-t)^2)
+   p2=vector.add(p2, vector.multiply(pointB2,2*t*(1-t)) )
+   p2=vector.add(p2, vector.multiply(pointC,t*t) )
+   p=vector.round(p)
+   p2=vector.round(p2)
+   line(data,area,p,p2,c_sample)
+  end
+
+ vm:set_data(data)
+ minetest.log("action", "rocks/genvein/ "..math.ceil((os.clock() - t1) * 1000).." ms ")
+end
\ No newline at end of file