Question: where do most useful minerals occur in nature
[{'answer': "Earth 's crust", 'provenance': [{'wikipedia_id': '19053', 'title': 'Mineral', 'start_paragraph_id': 101, 'start_character': 340, 'end_paragraph_id': 101, 'end_character': 355, 'bleu_score': 1.0, 'section': 'Section::::Classification.:Silicates.:Inosilicates.\n'}]}]