To purify, Cleanse or neutralize the energy of protection stones such as obsidian- lay them in top of a bed of selenite.
Selenite is very delicate, basically melts in batter and you can carve into the stone with your fingernails. Selenite is known, mostly- for purifying other stones and absorbing unwanted energy
Selenite is so delicate the pyramid shaped stone i had split like it was time to chop the firewood
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From @novus-locus