Minerals don't necessarily have to occur in a specific location within the Earth's crust. They can be found in a variety of places, including:

1. Igneous Rocks: Minerals form directly from the cooling and solidification of magma or lava. Examples include:

* Granite: Contains quartz, feldspar, mica

* Basalt: Contains plagioclase feldspar, pyroxene, olivine

2. Sedimentary Rocks: Minerals can be formed from the accumulation and cementation of sediments, or they can be dissolved and re-precipitated within the sediments. Examples include:

* Limestone: Primarily composed of calcium carbonate, often formed from marine organisms

* Rock Salt: Composed of halite, formed from the evaporation of ancient seas

3. Metamorphic Rocks: Minerals can be transformed from existing minerals due to heat and pressure. Examples include:

* Marble: Metamorphic equivalent of limestone, contains calcite

* Gneiss: Contains quartz, feldspar, mica, formed from the metamorphosis of granite

4. Ore Deposits: Mineral deposits that are economically valuable and can be mined. These deposits can occur in any of the above rock types or in hydrothermal veins. Examples include:

* Copper ores: Chalcopyrite, bornite, chalcocite

* Gold ores: Native gold, electrum

5. Weathering and Soil Formation: Minerals are released from rocks through weathering processes and can become part of the soil. Examples include:

* Clay minerals: Kaolinite, montmorillonite

* Iron oxides: Hematite, goethite

Therefore, the location of a mineral within the Earth's crust depends on its origin and formation process. It's not limited to a specific depth or rock type.