:salam2:
As per my little knowledge, “Men and Stones” appears together twice a time in the Holy Qur’an as “fuel of fire (hell)”. Word “Men” is understood but what we observe when we read word “stones”? I mean what kind of “stones” it could be?
Please share your knowledge. 
Re: Men and Stones
Wa alaikum us Salam!
LKK,
here are my two cents:
there are two possible interpretations of 'hajr':
1) In context of the verse 2:24), the stones are the idols they use to worship as in another verse, it is stated that
21:98) "Surely, you and that which you worship beside Allah are the fuel of Hell. To it shall you *all *come."
2) As the fire is for the disbelievers, men and stones both refer to the two classes of disbelievers:
a) Naas: lesser degree of culprits who can be regarded as humans
b) Hajar: those whose hearts are like stones . this is mentioned in another verse that states:
2:74) Then your hearts became hardened after that, till they were like stones or harder still;....