• سِّجِلّ
• سِجِّيل

Appears 4 times in the Quran.

1. 11:82 فَلَمَّا جَآءَ أَمْرُنَا جَعَلْنَا عَٰلِيَهَا سَافِلَهَا وَأَمْطَرْنَا عَلَيْهَا حِجَارَةً مِّن سِجِّيلٍ مَّنضُودٍ

   So when Our decree came to pass, We turned them upside down and rained down upon them stones, of what had been decreed, one after another.
   

2. 15:74 فَجَعَلْنَا عَٰلِيَهَا سَافِلَهَا وَأَمْطَرْنَا عَلَيْهِمْ حِجَارَةً مِّن سِجِّيلٍ

   Thus did We turn it upside down, and rained down upon them stones of what had been decreed.
   

3. 21:104 يَوْمَ نَطْوِى ٱلسَّمَآءَ كَطَىِّ ٱلسِّجِلِّ لِلْكُتُبِ كَمَا بَدَأْنَآ أَوَّلَ خَلْقٍ نُّعِيدُهُۥ وَعْدًا عَلَيْنَآ إِنَّا كُنَّا فَٰعِلِينَ

   On the day when We will roll up heaven like the rolling up of the scroll for writings, as We originated the first creation, (so) We shall reproduce it; a promise (binding on Us); surely We will bring it about.
   

4. 105:4 تَرْمِيهِم بِحِجَارَةٍ مِّن سِجِّيلٍ

   Casting against them stones of baked clay,