This is an alum crystal (potassium aluminum sulfate dodecahydrate). 1 piece ◯ (mi) is a symbol used to distinguish the seller. ◯ Size: Approximately 2.6-3.0cm on one side ◯ Weight: Approximately 21g ◯ It was made by submerging a seed crystal in a saturated solution and evaporating the water over time. The orientation was occasionally changed to bring it closer to an octahedron (lying-down method). ◯ The surface will turn white (effloresce) when dried, so it is recommended to store it in an airtight container. ◯ The corners are easily chipped if bumped. ◯ Please understand that this was created by an amateur, so there may be cloudiness, chips, scratches, small cracks, etc. #Alum #Crystal #Recrystallization #ScienceProject #Science #Experiment #Craft #Chemistry #ElementarySchool #MiddleSchool #ElementarySchoolStudent #EducationalMaterial #Teacher