______________ is actually a rock consisting of aluminium oxides.

Hematite ore is the most important industrial _____________.

____________ refineries act as a "nodal industry".

_____________ is the energy of modern world.

_____________ is mainly used in electrical cables, electronics and chemical industries.

Coal is classified into ___________ .

The _____________ minerals do not contain metals.

_______________ deposits are formed by the decomposition of a wide variety of rocks rich in aluminium silicates.

___________ is a hard, black and compact coal.

___________ is the hardest coal and ranks highest among the coals.