Mount Carbon is a census-designated place in Fayette County, West Virginia, United States. Mount Carbon is located along West Virginia Route 61, 3 miles southeast of Montgomery, on the south bank of the Kanawha River at the mouth of Armstrong Creek. Mount Carbon has a post office with ZIP code 25139. As of the 2010 census, its population was 428.Mount Carbon was named for nearby coal deposits, a carbon-based fuel.Mount Carbon has a rich archaeological history. In the early 20th century, Indian skeletons were found under the railroad tracks. Ancient tools and weapons were found near there, as well. On the mountain above the town, there was a discovery of a man-made wall stretching for about 10 miles, 2 wells, and grave sites, possibly relating to the Adena culture that inhabited the region from 250-100 BCE.