When scoring for marimba, be especially precise about the type of mallets and articulation you want, as different types favor different overtones. Watch the end of the Evelyn Glennie video I’ve linked below. There are intriguing possibilities with softer mallets, tremolo, and contrasting registers.

Marimba Mallet Choices
excerpt from the marimba part of my orchestral legend Maui’s Fishhook