Tourmalinated Quartz

Tourmalinated quartz is clear quartz with dark rods of tourmaline grown through it. Cunningham describes it as quartz pierced by crystals of black tourmaline, and Hall as clear crystal holding long, thick, dark threads, easy to obtain in any size and found the world over. Quartz itself is silicon dioxide, and tourmaline is a group of crystalline silicate minerals built around boron, according to Wikipedia. Its formal name is unsettled here because neither Hall nor Cunningham gives it a mineral name, and Wikipedia's Quartz article does not include it in its list of quartz varieties. Hall presents it as joining the qualities of both minerals: a grounding stone that shields the body's energy field from intrusion, eases tension, harmonises opposites and turns negative thought towards the positive, and she uses it to help heal the shadow side of the mind and to curb self-sabotage. Cunningham places it under Pluto. He suggests wearing it, or keeping it under the pillow, to encourage astral projection, or gazing into a sphere of it to quieten the mind before sending the astral body into the crystal.