Amber Ore occurs in deep underground rock layers, at a similar level to Diamond Ore. It can be mined with an Iron Pickaxe or better.
When mined, it has a 50/50 chance of dropping either a Mosquito in Amber, or an Aphid in Amber.
When extracted in a lab, a Mosquito in Amber always gives a (sometimes very good) DNA sample from a random land animal or ocean animal, and an Aphid in Amber always gives a (sometimes very good) DNA sample from a random land plant or tree.