Sage is used to cleanse and clear negativity from your space, home, yourself, your cards, pendulum, your crystals, and anything else that may need clearing. Also smells wonderful.
selenite is used to cleanse, clear and recharge your crystals. 
Selenite is said to be a powerful healing crystal that brings peace, calm, mental clarity, assists with meditation and removes negative energy and provides protection. A powerful combination paired with sage.