Crystals are formed when identical polyhedrons are aligned in a uniform pattern; mostly, this naturally occurs under pressure and heat. In alchemy, the heat and pressure are provided in a type of fire, wind earth transmutation, forcing the polyhedrons in an object of the user's choice to crystallize completely; any kind of material can be used in the transmutation, even air. However, the enemy of the crystal style alchemy is high-frequency sound, as it forces the polyhedrons to come undone from their pattern and the crystals to shatter. Not only that, but the user had to know nearly every exchange rate and mass of any element that they wish to crystallize. The reason Trisha was regarded for her ability was not only her unique form of alchemy in the style; but also her vast amount of knowledge on the exchange rates and the mass of any given element or object; however, not well known enough, as she was not an official state alchemist; merely a black-ops member, only performing dangerous and covert missions. Ed and Al are able to use this style as well, having most of the rates and masses known, but Rain has nearly perfected the style by using her perfect memory (a type of extreme obsessive compulsive disorder that's she's had since birth.)