Yes, the symmetry does matter. Quartz is trigonal, so its lattice repeats in a hexagonal pattern, and that defines the direction‑dependent speed of sound waves through it. In practice, a crystal cut along the 3‑axis will transmit vibrations differently than one cut along a 2‑axis, which is why quartz oscillators are precision‑cut. The regular, repeating symmetry lets the lattice support coherent phonon modes, giving quartz its low‑damping acoustic behavior. If you see a crystal that seems off‑spec, its internal symmetry is probably distorted, and the acoustic response will be inconsistent.

They’re not dead in the water, just less reliable. In low‑frequency, tolerant setups—like a simple tuning fork or a DIY resonator—the extra scattering in an off‑spec quartz can be acceptable. But if you need phase stability or a clean frequency, the symmetry break makes it unreliable. Use them only where the precision isn’t critical.