It’s an expansion resource, and as such it is found in areas that are not yet accessible (Jungle thralls, volcano area, etc). The obsidian nodes that currently exist are in that transitional area between the two biomes of the north and the volcano that we can currently access. While I believe gold will be rarer than silver, likely a rare spawn of the node similar to ice/black ice, I believe what we are seeing now is only a small bit of what will be available once the entire map is available.