From Halopedia, the Halo wiki
Muroto was deemed more viable by the Materials Group for the specific mining they required. Resources from Muroto were imported to Chi Ceti IV to be used in the creation of data crystal chips for the SPARTAN-II program. It was discovered early on that Muroto was incredibly rich with a particular light-weight, heavy-grade crystal needed for augmenting various armor composites. The mining facilities has faced many setbacks due to unrelenting storms and volcanic activity.
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