IPA: //ˈɑːrdʒənˌtaɪt//
KK: /ˈɑr.dʒənˌtaɪt/
A valuable mineral that is a source of silver, usually dark gray or black in color and has a shiny surface.
The miners discovered a rich vein of argentite deep in the mountain.
Argentite is derived from the Latin word "argentum" (meaning silver) and the suffix "-ite" (used to denote minerals or rocks). Thus, argentite refers to a mineral that is a form of silver.
Think of 'argentum' which means silver, and remember that 'argentite' is a mineral form of silver.