https://www.sciencedaily.com/releases/2022/07/220707100502.htm

One such material of interest has been muscovite mica (MuM). These minerals have the general formula KAl2(AlSi3O10) (F, OH)2 and have a layered structure consisting of aluminum (Al), potassium (K), and silicon (Si). Like graphene, MuM has gained attention as an ultra-flat substrate for building flexible electronic devices. Unlike graphene, however, MuM is an insulator.

However, the electrical properties of MuM are not altogether clear. In particular, the properties of single and few-molecule-layer thick MuMs are not clearly understood. This is because in all the studies that have probed the electrical properties of MuM so far, the conductivity has been dominated by a quantum phenomenon called "tunneling." This has made it difficult to understand the conductive nature of thin MuM.