Question

Describe the possible history of a single crystal/grain of quartz as it moves from one part of the rock cycle to another. You must tell the story of the quartz grain as it occurs in rocks and through processes. Describe and discuss the pathways and products.

Answer 1

Initially the quartz are crystallizes from the magma, and according to the Bowens reaction series the quartz is the last mineral to crystallize from the magma thus it is a low temperature mineral. The quartz crystallizes at a temperature around 573°C and is considered to the most stable mineral among all others. It is the second most abundant mineral after feldspar in Earth's crust. As it is formed at lower temperature nearer to the surface when exposed to weathering mainly physical weathering by different agents like river, glacier etc it is carried away from the source to site of suitable basin where deposition takes place and thus on depositing it forms rocks like sandstone and some other rocks which includes quartz as a accessory mineral. Variety of sandstones are formed based on quartz content it is classified. With further burial after the due to continuous deposition it imparts high pressure and temperature and thus it leads to metamorphism and forms quartzite which is a metamorphic equivalent of sandstone. These are the path ways and products where first igneous rock is formed then sedimentary rock and at last metamorphic rock. And the cycle repeats.