Nesquehonite
Nesquehonite is a mineral of magnesium carbonate. It represents the trihydrate of magnesium carbonate, and has the total formula.
It was described in 1890 by F. A. Genth and S. L. Penfield and is named after its type locality of Nesquehoning, Pennsylvania, where it was sampled from a coal mine. Nesquehonite can form from the related pentahydrate Lansfordite by dehydration at room temperature.