Rocks are naturally occurring solid aggregates of minerals or mineraloids, classified into three main types: igneous, sedimentary, and metamorphic, based on their formation processes. Articles are a unique way for readers to learn about the world around them. In addition to building reading comprehension skills and increasing vocabulary, articles can be used for writing and research. Rocks is broken into 6 single-page sections: Types of Rocks, Properties, Rock Cycle, Fossils, How Rocks are Used, Words to Know.