XIII. Class of Minerals

The thirteenth class of minerals includes organic substances that can be considered minerals. These are citrates, oxalates, and acetates formed by the reaction of a metallic cation with the corresponding organic acid under the influence of natural physicochemical processes that occur without human or other living organism involvement. This class also includes hydrocarbons, of which fichtelite can be considered a mineral, while petroleum, tar, ozokerite, asphalt, and various types of coal are considered rocks. Organic compounds containing oxygen that are not salts, such as fossil resins, with amber being the most well-known, were once included in this mineral class.