1. Weathering Resistance:
* Quartz: Quartz is a very hard and chemically resistant mineral. It's difficult to break down by physical weathering (like wind and rain) and chemical weathering (like acid rain). This means quartz survives the weathering process that forms soil.
* Feldspar: Feldspar is less resistant to weathering. It breaks down more easily into clay minerals, which are important components of soil.
2. Mineral Abundance in Parent Material:
* Quartz: Quartz is a common mineral in many rocks, including granite, sandstone, and other igneous and sedimentary rocks. These are common parent materials for soil.
* Feldspar: While feldspar is also common in many rocks, it's often weathered away during soil formation.
3. Soil Formation Processes:
* Chemical Weathering: As feldspar weathers, it releases potassium, calcium, sodium, and other nutrients that become available to plants. However, the feldspars themselves are often not directly present in the soil as they decompose.
* Clay Formation: The breakdown of feldspar contributes significantly to the formation of clay minerals, which are essential for soil structure and water retention.
4. Soil Type and Location:
* Quartz-rich Soils: Some soils, particularly those derived from quartz-rich parent rocks (like sandstone), will have a higher proportion of quartz.
* Feldspar-rich Soils: Soils developed from volcanic rocks (like basalt) or other feldspar-rich rocks might contain a higher proportion of feldspar before weathering.
In summary:
While quartz is abundant in soil, it's not because feldspar is scarce in rocks. Feldspar is crucial for soil formation as it provides nutrients and contributes to clay mineral development. However, feldspar weathers away relatively quickly, leaving behind the more resistant quartz.
