In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- Every impure substance is haram but not every haram substance is impure. For example poison is haram to ingest, but it is not physically impure.
Sheikh Abu Eesa Niamatullah elaborates more on this issue in this short video:
Almighty Allah knows best.