Apophyllite is a wonderful stone to use in a grid. It elevates the vibration of everything. This stone opens you up to new things that come completely from the light. It is not a stone that can bring in anything negative.
Another use for apophyllite is in meditation. If you want more clarity in your meditations, this is your stone. You can hear the voice of guidance loud and clear when using this stone for meditation.
Use this for clarity, awareness and transcendence.