Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: Weathering may concentrate some resources. In tropical climates, chemical weathering can be intense. Some minerals dissolve and water carries them away. This leaves behind the materials that are not soluble. Bauxite is aluminum oxide that collects this way. Bauxite is our main source of aluminum ore. Answer: bauxite
A:
What is our main source of aluminum ore?