Pyrite is a stone containing the essence of fire. It can also be obtained from ifrits.

Source

• The Great Book of Minerals
• The Last Wish

Notes

• In Chapter V, among the wounded on the streets of Old Vizima, there are female human Nurses and/or elven Paramedics. Sometimes Geralt can speak with them and they will ask for something. In return, any one of them will tell Geralt about ifrits, so Pyrite will most likely be added to the journal, too:
  • A Nurse asks for Naezan salts or Wine stone.
  • A Nurse asks for "healing brew".
  • A Paramedic asks for White Raffard's Decoction.
  • A Paramedic asks for Honeysuckle or Hop umbels.