Add a block in The End that cancels gravity underneath it.

Generation:

* Only generates in The End, but can be placed in any dimension.

* Generates randomly as single blocks or (very rarely) as a "patch" of 2 to 8 blocks.

* Would replace an Air block between 0 < y < 16 that is directly beneath Endstone and directly above another Air block.

* Voidstone might also be found at the top of masts of some End Ships as a Minecraft lore teaser.

* May or may not be limited in generation to End Islands. Or may generate in a solid amount beneath the main End Island (as a way to "crawl" beneath the island to the other side?) but may only sporadically generate in other End Islands.

Functionality:

* Gravity is canceled directly beneath the Voidstone block (same X/Z coordinates only) but only down to a certain relative depth. The range of this effect should be balanced.

* Mining difficulty is the same as obsidian (minimum diamond).

* Naturally-occurring Voidstone could be used to help craft End bases in the spaces below End Islands.

Possible Uses:

* Stacking Voidstone on top of one another might create a small levitation effect within a range above the top one?

* Voidstone might be used as a possible ingredient for extra-powerful rockets, craftable elytra, or something else.