The greyish solid that is shiny when sanded and is a metal is aluminium. Aluminium is a lightweight, silvery-white metal that is very ductile and malleable. It is the most abundant metal in the Earth's crust and is the third most abundant element after oxygen and silicon. Aluminium is used in a wide variety of applications, including:

* Construction: Aluminium is used in the construction of buildings, bridges, and other structures because it is lightweight and strong.

* Transportation: Aluminium is used in the construction of cars, airplanes, and other vehicles because it is lightweight and fuel-efficient.

* Packaging: Aluminium is used in the manufacture of cans, foil, and other packaging materials because it is lightweight and easy to recycle.

* Electrical: Aluminium is used in the production of electrical wire, cable, and other electrical components because it is a good conductor of electricity.

* Consumer products: Aluminium is used in the manufacture of a wide variety of consumer products, including cookware, appliances, and furniture.