Chemical Weathering of Silicate Rocks
Silicate rocks include all types of igneous rocks (the most common are granite and basalt), sandstone, shale, and most types of metamorphic rocks (slate, phyllite, schist, and gneiss). For soil-forming purposes, they are made of two types of minerals: quartz and everything else.
Quartz, or SiO2, has a very sturdy 3D tetrahedral framework structure that isn't affected at all by chemical weathering. Through mechanical weathering, quartz eventually becomes sand. After long-term weathering, all of the sand in the soil will be quartz.
Silicate rocks that are basically all quartz, like sandstone and metamorphic quartzite, will only produce sand. Silicate rocks that don't have any quartz at all, such as mafic igneous rocks (basalt), might not produce any sand. In between, how sandy the soil is depends on how much quartz the rock has and how long weathering has gone on to break down non-quartz sand-sized particles.
Everything else includes the ferromagnesian minerals (olivine, augite, hornblende, and biotite), garnet, feldspars, and micas. They have a variety of crystalline structures, from single and double chains of tetrahedrons, to 3D frameworks similar to quartz, to sheets. Early in the development of a soil, some of these will be sand-sized particles, especially feldspar. Under chemical weathering in the long-term, all of these become clay minerals (kaolinite, montmorillonite, talc, and many others), which have a sheet structure that occur as tiny flakes.
Clay minerals have a negative electrical charge on the flat parts of the flakes. This allows them to attract and hold water molecules and positive ions like Ca++ and K+, which are important plant nutrients.