Amethyst Stone Block

Gem blocks form small pockets through the underground and cavern layers, and the color showing in the rock is the tell that a gem cluster is embedded there. Mine one and you get the gem rather than the block, which is exactly what you want on a first pass, since the gems go into hooks, staves and phasesabers.

If you want the block itself you have to make it, and the setup costs more than the block suggests. You need a Graveyard first, which means clustering enough tombstones in one spot to raise the ecto mist, then standing a Heavy Assembler inside that mist. From there a stone and a gem gives you the block, and the matching wall comes off a plain work bench in the same mist.

Worth the trouble if you want colored stone accents that still read as natural rock, and hard to justify otherwise while gems are still going into gear. On the old console and 3DS versions the block cannot be obtained at all, so it stays purely scenery there.