An unused material is present in the game's code. It is broken faster by swords, has a foliage color, and is destroyed by pistons. However, no blocks actually use the material.
Code in question is in this comment
Comments 27
Anthony Cicinelli materials don't have specific textures, as far as I know, they just have different blocks that use that material.
I'm reopening this and leaving it to Mojang's decision, as I don't think the "unused code" speaking from an optimizer's POV applies here.
Can you post an image of this material