Question: where can barium be found in the world
[{'answer': 'never found in nature', 'provenance': [{'wikipedia_id': '3757', 'title': 'Barium', 'start_paragraph_id': 1, 'start_character': 201, 'end_paragraph_id': 1, 'end_character': 222, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '3757', 'title': 'Barium', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 370, 'bleu_score': 0.893438927867214, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 1903683923874707835}, 'section': 'Section::::Abstract.'}]}]