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:
Alps

Context:
The Alps are a source of minerals that have been mined for thousands of years. In the 8th to 6th centuries BC during the Hallstatt culture, Celtic tribes mined copper; later the Romans mined gold for coins in the Bad Gastein area. Erzberg in Styria furnishes high-quality iron ore for the steel industry. Crystals are found throughout much of the Alpine region such as cinnabar, amethyst, and quartz. The cinnabar deposits in Slovenia are a notable source of cinnabar pigments.

Question:
What did the Romans mine in the Bad Gastein area?

gold