[qtdyyraw] Ulam spiral mining

Create a mining game in which the valuable deposits are arranged as the primes in an Ulam spiral.  There are rich veins. 

Unfortunately, this won't Just Work in Minecraft.  There are two major types of veins on an Ulam spiral.  One type (more famous) is diagonal.  The other type is on a horizontal or vertical line, but primes alternate with composites along the line.  In neither type does the next deposit become visible after mining a block.  However, we would like such visibility to encourage a player to continue mining along a vein.

Maybe rocks become slightly different colored if they have a neighbor that is a deposit.  This resembles Minesweeper.  Maybe an edge lights up to signal a diagonal vein.  Similarly, a vertex glows to signal a space diagonal vein (assuming we have veins oriented along space diagonals).

Rotating the Ulam spiral 45 degrees and using only half the squares, one color of a checkerboard, gets the formerly diagonal veins, but not the other type (which now become diagonal).

And of course, we would need to deal with the fact that Ulam spirals are 2D and Minecraft is 3D.

We considered the Ulam spiral drawn on a hex grid as initially promising because there aren't hexagons that meet only at corners, but, upon examination, this Ulam spiral is not aesthetically pleasing.  In some sectors, there are veins of primes along adjacent cells, but in other sectors, veins go "diagonally" (cells separated by an edge), or alternate with composites.