1. Basalt:
* Color: Dark gray to black
* Texture: Fine-grained, often with small, visible crystals (vesicles)
* Other: Often has a "frothy" or "bubbly" appearance due to trapped gas bubbles. Common in volcanic areas.
* Recognition: Feels heavy, and has a slightly rough texture.
2. Granite:
* Color: Light gray to pink
* Texture: Coarse-grained, with large, easily visible crystals.
* Other: Often contains quartz (clear/milky) and feldspar (white/pink/gray) crystals. Very hard and durable.
* Recognition: The large, distinct crystals are a key giveaway. Found in mountainous areas and often used for construction.
3. Rhyolite:
* Color: Light gray to pink
* Texture: Fine-grained, with very small crystals or even glassy.
* Other: Can have a "flow" texture, resembling stripes or lines.
* Recognition: Similar to granite in color, but much less coarse-grained.
4. Gabbro:
* Color: Dark gray to black
* Texture: Coarse-grained, with large, easily visible crystals.
* Other: Looks similar to basalt but has larger crystals.
* Recognition: Feels heavy and has a rough texture.
5. Obsidian:
* Color: Black, dark brown, or green
* Texture: Glassy, with a smooth, conchoidal fracture (breaks in curved, shell-like shapes).
* Other: Often found in volcanic areas where lava cools quickly.
* Recognition: Shiny, reflective surface that feels smooth but can be sharp.
Remember: These are just basic guidelines. There is a lot of variation within each rock type, and other factors like weathering and mineral composition can affect their appearance.
