Stones as Fuel

S 2:24 And if you have not done so, and you will not do so, then fear the fire whose fuel is people and stones, prepared for the kafirun.

S 66:6 Those who have believed, protect yourselves and your family from a fire whose fuel is people and stones. Over it are angels, harsh, severe. They do not disobey Allah what he has commanded them and they do what they are commanded.

How might stones serve as fuel? Do they burn? Is hell fire fuelled by stones? Do the above-mentioned angels go in search of stones to serve as fuel?

Are believers to guard themselves and their family from hell fire? According to S 19:71-72, all Muslims wind up in hell. See: The Quran on Muslims Entering Hell Are there angels, plural, in charge of hell? But isn't one Malik supposed to be the one over hell? Allah’s Need for Human Sacrifice to Appease Hell’s Angelic Ruler – Answering Islam Blog The last sentence of S 66:6 repeats the thought that hell's angels obey.