"A well—polished crystal. It contains a card inside. I could obtain the card if I crack it."
— Item examination - English
— Item examination - Japanese
The Crystal (水晶 suishō ) is a key item obtainable in Resident Evil CODE:Veronica.
It is to be put on the floor near the cannon, under the chained block that keeps dropping to smash the crystal and to retrieve the Security Card. Caution is needed since the block will kill Claire if she's still under it when it drops.
This item is found in the underground detention chamber on level B4 of the Antarctic Base after interacting with the cannon.