Obsidian gravel is a block quite similar (in colour and apperance) to Mordor gravel. It is found in rather rare deposits all through the Far Harad jungle and the Far Harad Volcano. You can mine it like every other gravel block, but it doesn't drop flint.
The gravel can be used for building and decoration purposes. More importantly, it can be ground in a millstone for obsidian shards, which are useful in creating Taurethrim equipment. It may be easier to mine and break down obsidian blocks rather than to seek and gather obsidian gravel. Like other gravel blocks, obsidian gravel responds to gravity.
Cloud forest •
Corsair coasts •