In blockstates
{
    "variants": {
        "normal": { "model": "davesmod:obsidium_block" }
    }
}

In models\block
{
   "parent": "block/cube_all",
   "textures": {
       "all": "davesmod:blocks/obsidium_block"
   }
}

In models\item
{
   "parent": "davesmod:block/obsidium_block"
}