Methods of controlling crystal polymorphism in organic-free synthesis of Na-Zeolites and the zeolite crystals formed using those methods are provided. The methods disclosed herein create certain types of zeolite crystals more efficiently than other previously known methods. The methods also create certain types of zeolite crystals in a form and concentration not previously disclosed. The methods disclosed herein generally comprise using solutions with varying ratios of silicon (Si), aluminum (Al), hydroxide (OH), and water. Some implementations of the invention disclosed include efficient methods of producing nearly pure cancrinite (CAN), methods of obtaining sodalite in solutions with a high Si/Al ratio, and a method of forming thin, platelet-like ANA crystals with a width of less than about 1 μm and a length of at least about 3 μm.