Rocks can have varying properties and are not always hard, solid, natural, or composed solely of minerals as initially thought. Rocks are classified based on their formation process, with the main types being igneous (formed from cooling magma), metamorphic (formed from existing rocks undergoing heat and pressure), and sedimentary (formed from compression of sediments over time). The document serves to dispel preconceptions about rocks and introduce how they are scientifically classified according to their formation.

1. Rocks Rock!

2. Before we look at rocks, let’s review the characteristics of minerals. Naturally occurring Definite crystalline structure Definite chemical composition Solid Inorganic Used for building materials, gemstones, health supplements, toothpaste, medical, baby powder, etc.

3. What do you know about rocks? Do you agree with these statements? Rocks are hard. Rocks are solid. Rocks are natural. Rocks are made of minerals.

4. Rocks are hard. Not always… Some rocks are soft and can be scratched with your fingernail (shale, gypsum) Other rocks are soft until they are exposed to air, or visa versa.

5. Rocks are solid. Not always… Some rocks contain water in pores. Geodes hold water and minerals inside. Some igneous rocks are threaded or have fine meshwork, like Pele’s hair.

6. Rocks are natural. Not always… Consider everything that humans make.

7. Rocks are made of minerals. Not always… Remember that minerals are made of inorganic material. What about coal? What about coquina? What about obsidian?

8. So what are rocks then???