Question: what term is used to describe the value given to a coin because of its metal content
[{'answer': 'metal values', 'provenance': [{'wikipedia_id': '7558', 'title': 'Coin', 'start_paragraph_id': 55, 'start_character': 773, 'end_paragraph_id': 55, 'end_character': 785, 'bleu_score': 1.0, 'section': 'Section::::Value.:Currency.\n'}]}, {'provenance': [{'wikipedia_id': '7558', 'title': 'Coin', 'start_paragraph_id': 55, 'start_character': 0, 'end_paragraph_id': 55, 'end_character': 1245, 'bleu_score': 0.9743164403650171, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12662972764190353516}, 'section': 'Section::::Value.:Currency.\n'}]}]