spessartite (n.)

manganese garnet, 1853, earlier spessartine (1837), from French spessartine (1832), from Spessart, district in Bavaria where it is found.

Common garnet generally contains manganese as a component ; which is observable in the colour of the globule that results from melting it with soda. One variety, which contains no lime, has been called spessartine, from its locality, Spessart. ["Conversations on Mineralogy," 1837]