The GE locomotives - named For Mothers and Women of the North - join Roy Hill's existing 21-strong fleet at Port Hedland's rail yard.
The pink engines will be fashionably matched with 130 pink ore cars specially made by the China Railway Rolling Stock Corporation.
At the locomotive's official christening at the port Rinehart said For Mothers was named in honour of all mothers, especially those affected by breast cancer and related cancers.
"This dreadful disease is still the most commonly diagnosed cancer in Australia, with eight women dying from the disease every day [which is] far, far too many," she said.
"May these pink trains continue to inspire us to do more for breast cancer patients and support research to help fight this truly terrible and sad disease."
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