Conversation so far:
What was the Spirit's main discovery?
The rocks are a type of basalt.
Which Martian rocks were analysed after the spirit rover mission was completed?
What materials do Martian rocks contain after the spirit rover mission was completed?
They contain the minerals olivine, pyroxene, plagioclase, and magnetite, and they look like volcanic basalt as they are fine-grained with irregular holes.
Where were the rocks found during the spirit rover mission?
The plains of Gusev

Question: How did water alter the Martian rocks?
Self-contained rewrite: How did water alter the Martian rocks found during the spirit rover mission?