1. Igneous rocks: Formed from the cooling and solidification of molten rock (magma or lava). These rocks are typically dense and have few or no interconnected pores. Examples include granite, basalt, and obsidian.

2. Metamorphic rocks: Formed when existing rocks are transformed by heat, pressure, and chemical reactions. While some metamorphic rocks can be porous, many are dense and non-porous due to the recrystallization process. Examples include marble (formed from limestone) and quartzite (formed from sandstone).

Let me know if you would like more examples or want to explore other types of rocks!