The Thauminite Nugget is a component added by Thaumic Bases. It is used to craft Thauminite Ingots, which in turn can be used to craft Thauminite tools which have higher enchantability than Thaumium.
A thaumaturge always searches for a better alternative to his materials. You have been playing around with Thaumium metal for a while now... Maybe it's time to move onwards. Maybe it's time to improve. Thaumium can be processed further with addition of more aspects and some Vitreus. However, the processing of thaumium is too inefficient and leads to some thaumium destruction - and you do not see a way to overcome this problem. The result is a new metal, better than thaumium. It is almost as hard as diamonds and has much better enchantability than thaumium. It is also more magical, and can be used in some advanced things thaumium can't be used in...