This is a piece of raw Amethyst cluster approximately 12cm x 8cm and presented in a darker purple form.  Amethyst is an extremely powerful and protective stone with a high spiritual vibration.  It guards against psychic attack, turning the energy into love.  It is a natural tranquilizer blocking geopathic stress and negative environment energies.  Its serenity enhances higher states of consciousness and meditation.*
* Judy Hall "The Crystal Bible" 2009