1) Uranium mineral 
Weeksite is a naturally occurring uranium silicate mineral with the chemical formula: K2(UO2)2Si6O15•4(H2O), potassium uranyl silicate. Weeksite has a Mohs hardness of 1-2. ==Appearance== Weeksite is visually similar to other uranium minerals such as carnotite and zippeite, both being encrustations that form on other rocks (usually sandstones or...