Glass marbles are generally not good conductors of electricity or heat. Glass is an amorphous solid, meaning it does not have a regular, repeating structure at the molecular level. As a result, electrons and heat energy cannot flow through the material as easily as they can through metals, which have a crystalline structure with regularly arranged atoms. While there are some types of specialised glasses that can be made to conduct electricity (e.g. doped semiconductors), ordinary glass marbles fall into the category of insulators because electrical resistance is very high.