Here are a few rocks and crystals and their properties.
Agate, Chalcedony, Jasper, Onyx
Used for balancing the forces of Yin and Yang within the human bodies. Also balances the physical against the emotional. Awakens latent talents, promotes spiritual connectedness, mental stability and decision making. Used for aura cleansing and the elimination of negativity.
Amethyst
Promotes spirituality, contentment, stability, strength and peace. Use to balance and raise the psychic energies to a higher plane. An excellent stone for meditation, producing a calm and peaceful state and helping to maintain it. Opens and activates the Sahasrara Chakra. Protects against psychic attack. Provides the "sense" of common sense. Gives flexibility in decision making and prosperity in business. Aids the assimilation of new ideas. Used to treat hearing disorders. Strengthens the skeleton and assists good posture. Vitalizes and cleanses the autonomic nervous system and the endocrine glands. Also helpful with disorders of the nervous system generally, the digestion, heart, stomach, skin, and teeth.
Bloodstone
Enables contact with the ancestral spirits. Dispels bewilderment and obscurity of thought. Used for treating disorders of the blood, kidneys, intestines, liver and circulation. Promotes the elimination of toxins. Has been used effectively in some cases of leukaemia.
Citrine
Used for aura cleansing and alignment. For disorders of digestion, the blood, thyroid and thymus.
Garnet
A stone of health, which extracts negative energies from the Chakras. Promotes commitment to purpose and to self, with correctness of purpose and direction, leading to success. Enables connectivity to other worlds. Used in the treatment of disorders of the spinal column, bones, heart, lungs and blood.