Chemical weathering causes iron in rock to oxidize, and when iron oxidizes it produces iron oxide, more commonly referred to as rust. Given these facts, rust of iron in rocks is a direct result of  among the following options:
- solar heating
 - high speed fall from space
 - Chemical energy
 - The area was once underwater
 - permineralization
 - Temperature
 - volcanic ejection
 - chemical weathering


 

        chemical weathering 