Mid 19th century; earliest use found in Thomas Thomson. From German Marmatit from the name of Marmato, a village in western central Colombia, where it was first identified + -it.
Definition of marmatite in US English:
marmatite
nounˈmɑːmətʌɪt
Mineralogy
A ferroan variety of sphalerite.
Origin
Mid 19th century; earliest use found in Thomas Thomson. From German Marmatit from the name of Marmato, a village in western central Colombia, where it was first identified + -it.