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| Rocks and Minerals |
| Shale |
| Hornfels |
| Diabase |
| Limonite |
| Greenstone |
| Rhyolite |
| Quartzite |
| Conglomerate |
| Limestone |
| Sandstone |
| Calcite |
| Quartz |
Rhyolite |
| Often identified by its grayish color and sharp edges, rhyolite is a metamorphic rock that can be found in a few areas in the mountains of Frederick County. |
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