Quartz is a widely used material for its piezoelectric properties. This means that it can generate an electric charge when subjected to mechanical stress, and vice versa, it can also deform when an electric field is applied to it.

Option 1, Hg (mercury), is not the correct answer. While mercury does have some unique properties, it is not commonly known for being used as a piezoelectric material.

Option 2, Si (silicon), is the correct answer. Quartz is a form of silicon dioxide (SiO2) and is one of the most abundant minerals in the Earth`s crust. Its unique crystal structure allows it to exhibit strong piezoelectric properties, making it an ideal material for various applications such as sensors, oscillators, filters, and actuators.

Option 3, Ti (titanium), is not the correct answer. Although titanium has many impressive properties, it is not typically used as a piezoelectric material.

Option 4, Sn (tin), is also not the correct answer. Tin is not known for its piezoelectric properties.

In conclusion, quartz, which contains silicon (Si), is extensively used as a piezoelectric material due to its ability to generate an electric