MIDDLE SCHOOL SCIENCE STUDENTS INVESTIGATE: DOES QUARTZ ALWAYS FORM A HEXAGONAL PRISM?

Seventh grade science students conducted an experiment to determine if quartz always forms a hexagonal prism shape as defined by its symmetry: having 6 parallel sides. To answer this question, students measured a total of 196 singly-terminated quartz crystals from five United States localities. On each crystal, the width of the top and bottom of the six m-faces were measured as a ratio; with a ratio of 1 indicating that the sides are parallel and ratios greater than 1 indicating tapering, or non-parallel sides. Students then compiled the ratio data to analyze patterns quantitatively. The students observed that the crystals fell into two categories; crystals that fit the hexagonal prism definition (with ratios approximately 1) or crystals with ratios that showed a pattern of tapering on alternating faces that appeared trigonal in form. The amount of tapering varied between the five localities with alternating faces showing ratios that were at times much greater than 1. Based on the ratio data, students concluded that quartz crystals do not always form a hexagonal prism with parallel sides but can also form crystals with tapering, trigonal shapes. This natural variation that produces two populations of quartz with different habits warrants further study as current literature does not provide an adequate explanation for the phenomenon the students measured. The final project results were presented at the Tucson Gem & Mineral Show and at a local Mineral show in Grass Valley, CA in 2024. To study an authentic science question and collect quantitative data that reveals patterns that have not been fully described in science made the learning more profound and engaging to the students. The implications for Earth Science education at the secondary level are that teachers can involve students in “real science” to develop skills of making detailed, quantitative measurements, systematic data collection and graphical analysis of patterns. For students, using real quartz crystals with natural variations piqued their interest to look more closely and identifying a new idea for science made them think more deeply. Using this student-driven technique, future Earth Science experiments could be developed to identify form variations using only incomplete crystals to determine their geometry.