The extensive development of tourmalinites is a major feature that distingui- shes the northern Guangxi tin polymetallic metallogenic province of China from the other similar metallogenic provinces (belts). There are two types of tourmalinite in the province. The first type, occurring in the lower part of the Lower Proterozoic Sibao Group, is bedded, stratoid or lenticular tourmalinite. The laminated structure and gel and degel structures are well developed in this type of tourmalinite. Its mineral composition is very simple and the grain size of the minerals ranges from 2 to 8 μm. Tourmaline is rich in Mg, with a Fe0/(Fe0+Mg0+Mn0) ratio of 0.191-0.653. The second type of tourmaliinte occurs as lodes and is strictly controlled by faults. It is distrbuted in the exocontact zone of Late Proterozoic biotite granite. Its mineral composition is relatively complex; the minerals are present in euhedral or subhedral crystals ranging in grain size from 0.1 to 3.5mm, mostly from 0.5 to 1 mm. Tourmaline usually exhibits radiating and zoned structures, with a Fe0/(Fe0+Mg0+Mn0) ratio of 0.639-0.849. On the basis of the above-mentioned features coupled with geochemical studies and an extensive correlation of research results of tourmalinites from various parts of the world, it is suggested that bedded tourmalinite was formed by exhalation in an Early Proterozoic continental-margin depression, while lode tourmalinite was formed in a plate conergence environment and was genetically associated with Late Proterozoic biotite granite. As tourmalinites themselves are orebodies or mineralized rocs in the study region, the origin of the tosrma in tes and their evolution in the geological history also reflect the form ation ana evolution of tin polymetallic deposits.