Final answer:
Quartz is the most stable mineral on the Earth's surface because it is the stable polymorph under those conditions. Other minerals like biotite, pyroxene, and plagioclase are less stable compared to quartz.
Step-by-step explanation:
The most stable mineral on the Earth's surface is quartz. Quartz is a mineral consisting of silicon dioxide (SiO2) and is found in all rock types. The stability of quartz at the Earth's surface is due to it being the stable polymorph in such conditions, compared to minerals such as biotite, pyroxene, and plagioclase feldspar.
In contrast, biotite is a form of mica that is less stable at Earth's surface conditions, as it can undergo chemical weathering more readily.
Pyroxene and plagioclase feldspar are also less stable in surface conditions compared to quartz. Silicon and oxygen are the two most abundant elements in the crust, and the silicates, which include quartz, account for approximately 90% of the Earth's crust.