We are now reporting that Mg-C-O-H compound which has a Mg hydroxide symmetry, Mg(OH)₂, whose mineral name is Brucite, is an excellent electrical conductor with high optical transparency. We believe that this new material is the first non-oxide type transparent conductor. The compound has approximately 90% of optical transmission and conductivity of approximately 10^-2 Ωcm with 2.4 μm of thickness. The compound was fabricated through two consecutive processes. First Mg-C films were prepared by magnetron sputtering. Then, post-treatment was done to make the Mg-C react with moisture in the air. These processes yielded Mg(OH)₂-C. In this paper, the fabrication processes and optical and electrical conductive properties of the compound will be reported and possible origin of the excellent properties will be discussed. [DOI: 10.1380/ejssnt.2009.791]