How are minerals and rocks classified? What are they classified by?

Mineral classification can be an organizational nightmare. With over 3,000 different types of minerals a system is needed to make sense of them all. Mineralogists group minerals into families based on their chemical composition. There are different grouping systems in use but the Dana system is the most commonly used. This system was devised by Professor James Dana of Yale University way back in 1848. The Dana system divides minerals into eight basic classes. The classes are:native elements, silicates, oxides, sulfides, sulfates, halides, carbonates, phosphates, and mineraloids.