Gold Pickaxe is a Pickaxe. It deals 2.5 tile damage (per hit) to 3x3 area. It has 800 durability. See the page Pickaxe for "how it works" information.
It can be crafted at tier 1 and is extremely practical to use when exploring the depths of the starting Garden planet. Later in the game it becomes outclassed by a much more durable Carbon Pickaxe.
Improved Mining (Engineering tree).