Marabel, victor, and herbie were familiar with detention. their reputation as the greatest fifth-grade pranksters in their school's history had landed them there at least a dozen times before. but on this particular day, something seems different. for starters, they are under the not-so-watchful eye of ms. pebbles, the fifth-grade science teacher and school hermit. but there's something else peculiar about this detention: a hardhat.sure, there's nothing special about it at first glance, but this hardhat will take the trio on the adventure of a lifetime. whether to the tallest mountain peaks, or to the secret underground world of a people made of stone, the magical hardhat leads the fifth graders on the most important mission of their lives. a mystery rock or mineral is about to be stolen, and it's up to the maniacs to use their unique gifts to figure out the identity of the mineral before it's taken from the world forever. this fun and educational series will excite even the youngest readers, and will inspire future generations of innovators, educators, and engineers to be forces of positive change in the world. bonus: includes a supplemental section for students and educators alike about how the mineral is formed, mined, processed, and used in our everyday life.