Final answer:
Feldspars weather to form clays through a process of chemical weathering. Clays are composed of fine particles that include weathered feldspar, which gives them their color and plasticity. The presence of feldspar in sedimentary rocks like arkose suggests a closeness to the source rock and minimal transport.
Step-by-step explanation:
The student asked which product feldspars weather to. Feldspars are a group of rock-forming minerals that are known to weather chemically to form clays. The weathering process involves the breakdown of feldspar over millions of years under natural conditions. This process occurs as pre-existing rock is exposed to elements such as water and carbon dioxide, which can cause chemical reactions leading to the breakdown of minerals.
Feldspars crystallize from magma as veins in both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. They cool below the earth's surface, generally deep, where they cool gradually and slowly, which allows individual crystals time and space to grow large. Feldspars crystallize early in the cooling process, which leads to their characteristic straight crystal sides.
Clays are a key product of the weathering of feldspar. They consist of fine particles of silt which include weathered feldspar, silica, and alkalis like iron that give clay its color. In the creation of clastic sedimentary rocks, feldspar alters into clay through chemical weathering. For example, arkose is a type of sandstone containing a significant amount of feldspar, which indicates proximity to the source rock and that the sediment has not been transported over long distances. Hence, the correct answer to the student's question is A. clays.