Rocks
*Igneous Rocks:**
1. **Granite:**
- **Characteristics:** Coarse-grained, primarily composed of quartz, feldspar, and mica minerals.
2. **Gabbro:**
- **Characteristics:** Dark-colored, coarse-grained rock composed mainly of pyroxene, plagioclase, and olivine minerals.
3. **Basalt:**
- **Characteristics:** Fine-grained, dark-colored rock formed from rapidly cooled lava; rich in iron and magnesium.
4. **Obsidian:**
- **Characteristics:** Volcanic glass; smooth, shiny, and usually black; forms from rapidly cooled lava.
5. **Pumice:**
- **Characteristics:** Light-colored, porous rock with many gas bubbles; often floats on water; formed from frothy lava.
6. **Rhyolite:**
- **Characteristics:** Fine-grained, light-colored rock containing high silica content; often found in volcanic areas.
7. **Scoria:**
- **Characteristics:** Dark-colored, vesicular (contains gas bubbles) rock; forms from lava with high gas content.
**Sedimentary Rocks:**
1. **Breccia:**
- **Characteristics:** Coarse-grained rock composed of angular fragments; cemented together.
2. **Conglomerate:**
- **Characteristics:** Coarse-grained rock made of rounded pebbles and gravel; cemented together.
3. **Sandstone:**
- **Characteristics:** Medium to coarse-grained rock composed of sand-sized grains; often forms in deserts or underwater.
4. **Siltstone:**
- **Characteristics:** Fine-grained rock composed of silt-sized particles; smooth texture.
5. **Shale:**
- **Characteristics:** Fine-grained, layered rock composed of clay minerals; breaks into thin sheets.
6. **Limestone:**
- **Characteristics:** Sedimentary rock composed of calcium carbonate; often contains fossils; reacts with acids.
7. **Rock Salt:**
- **Characteristics:** Forms from the evaporation of salty water; composed of halite crystals.
8. **Coal:**
- **Characteristics:** Organic sedimentary rock formed from plant remains; varies in hardness and carbon content.
9. **Bituminous Coal:**
- **Characteristics:** Soft, black coal with relatively high carbon content; widely used as a fuel.
**Metamorphic Rocks:**
1. **Anthracite Coal:**
- **Characteristics:** Highest rank of coal; very hard, shiny, and black; forms from bituminous coal under high pressure and temperature.
2. **Gneiss:**
- **Characteristics:** Coarse-grained, banded rock with alternating layers of minerals; exhibits foliation.
3. **Phyllite:**
- **Characteristics:** Fine-grained metamorphic rock with a glossy sheen; intermediate between slate and schist.
4. **Schist:**
- **Characteristics:** Medium to coarse-grained rock with visible mineral grains; exhibits schistosity (foliation).
5. **Slate:**
- **Characteristics:** Fine-grained, smooth-textured rock; easily split into thin sheets; formed from shale.
6. **Marble:**
- **Characteristics:** Crystalline, metamorphic rock composed of recrystallized calcite or dolomite; often used in sculptures and buildings.
7. **Quartzite:**
- **Characteristics:** Hard, metamorphic rock primarily composed of quartz grains; formed from sandstone under heat and pressure.
**Other Mineral:**
1. **Diorite:**
- **Characteristics:** Coarse-grained, intrusive igneous rock composed of plagioclase feldspar, biotite, hornblende, and/or pyroxene.
2. **Pyrite:**
- **Characteristics:** Metallic luster; often called "fool's gold"; composed of iron sulfide; commonly found in sedimentary rocks.