Dragons are well known for their breath weapons in fiction, and there are four main types of breath weapons in my world that I am trying to make more scientifically accurate. I am focusing mainly on crystal breath, used by crystal wyrms. This breath weapon is shot as a pressurized beam or stream and corrodes stone, coating it in crystal.
What biological processes could allow for this crystal breath? The other dragons with breath weapons generally spray a mist that causes the effect, except fire breath, which uses a liquid, so both have precedent within the dragon family. The crystal wyrms live in crystalline caves, which may help with how they produce the crystals in case that helps.