All matter is an expression of energy. Some forms, such as crystals and metals, serve as better conduits than others. For example, quartz has piezoelectric properties commonly employed as crystal oscillators in watches and clocks to keep precise time.
In holistic healing, many forms of quartz and other crystals are known to hold certain properties that will yield a beneficial effect in the environment or person they are placed with. I have found them especially useful in chakra work to clear away stagnant energy and spark a needed dose of clarity for creativity and reflection. Depending on how far you want to venture, some say that each crystal serves as a teacher seeded with wisdom that will unfold when the right individual or frequency presents itself.
In my experience, crystals and other stones have a definitive resonance I can sense. Whenever possible I prefer to “feel out” prospective pieces before I purchase them. I seek out ones that sing to me, and they will not always be the most gleaming or beautiful examples in appearance. Person by person, the vibration felt will depend on the relative magnitude of the specimen and one’s sensitivity.
As in any esoteric realm when questioned about a certain practice or tool I always encourage personal experimentation. Opinions without experience are merely assumptions. Enter into the unexplored with an open mind and you will be inspired by what you discover.