The mineral formed by the weathering of feldspar and other silicate minerals, which is a principle component of clay shale, is kaolinite.

Here's a breakdown:

* Feldspar: A common mineral in igneous and metamorphic rocks.

* Weathering: The breakdown of rocks and minerals due to exposure to the elements (water, wind, ice, etc.).

* Kaolinite: A clay mineral formed by the chemical weathering of feldspar and other silicate minerals.

The process of kaolinite formation involves the breakdown of feldspar into its constituent elements, including aluminum, silicon, and oxygen. These elements then recombine with water to form kaolinite.

Clay Shale is a sedimentary rock that is composed primarily of clay minerals, including kaolinite.