The Piezoelectric Effect on Natural Quartz Crystals
Even well-ordered single crystals have many resonance modes at different frequencies. A natural cluster of quartz crystals might have a confusing jumble. Like doing resonance analysis of a model doing a catwalk strut.
Bragg x-ray diffraction was (is?) used to probe lattice structure to find alignment of crystal planes. X-ray tools can also be used to probe stress applied to crystals.