You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Portugal

Context:
Portugal is a significant European minerals producer and is ranked among Europe's leading copper producers. The nation is also a notable producer of tin, tungsten and uranium. However, the country lacks the potential to conduct hydrocarbon exploration and aluminium, a limitation that has hindered the development of Portugal's mining and metallurgy sectors. Although the country has vast iron and coal reserves—mainly in the north—after the 1974 revolution and the consequent economic globalization, low competitiveness forced a decrease in the extraction activity for these minerals. The Panasqueira and Neves-Corvo mines are among the most recognised Portuguese mines that are still in operation.[citation needed]

Question:
What mineral is Portugal ranked as a leading European producer of?

copper