psammite
/ˈsamʌɪt/Geology
noun
Originally: †a fine or smooth-grained sandstone (obsolete ). In later use: a sedimentary rock composed of medium-sized particles (commonly defined as those with a diameter between 1/16 mm and either 2 or 4 mm).
Origin
Early 19th century. From French psammite from ancient Greek ψάμμος sand + French -ite.