One of the reasons rocks and minerals are important to us is because they can be used to create and conduct electricity. A conductor is a substance that current (a flow of electric charges) is able to easily flow through, and an insulator is a material that current cannot flow through. Kidder has created a device that is able to detect the conductivity of certain rocks, minerals and just about any inanimate object/material. Place both ends of the alligator lead to the object and if the buzzer goes off it is conductive! Simple as that. *Rocks & 9V battery not included*