Carnelian is a chalcedony that contains iron and is formed in the vicinity of alkaline and acid volcanic rock out of magmatic silicic acid solutions.  Used in the Middle Ages, carnelian was assigned a blood-staunching and anger-calming effect. Hildegard von Bingen recommended carnelian as a stone to ease headaches and as a useful birthing aid. Carnelians were used in Ancient Egyptian magic as protection for both the living and the dead. A stone of courage, in Roman times a carnelian was engraved with the head of a lion or a great leader.
Spiritually carnelian promotes steadfastness and encourages a spirit of community. It makes us willing to help, be idealistic, and stand up zealously for a good cause. Use carnelian as a focus for past-life work and for finding a twin soul. Carnelian is especially good for rekindling or increasing passion that has faded in an otherwise loving relationship. Place a carnelian under each corner of the mattress. Wearing a carnelian will act as a shield from attempted psychic intrusion into your thoughts.
Emotionally carnelian is a powerful protector against envy, rage, and resentment, yours or other peoples. It calms anger and banishes emotional negativity, replacing it with a love of life. Carnelian bestows courage - not the risky heroic courage but everyday courage to overcome and stand up to difficulties.
Mentally carnelian encourages the facility to solve problems quickly and pragmatically. It brings actions once begun to a proper conclusion and a sense of reality whenever you are feeling confused. This beautiful stone promotes positive life choices, dispels apathy, and motivates for success in business and other matters. Carnelian helps you to trust yourself and your perceptions. It gets to the bottom of what makes you tick, and overcomes negative conditioning. 
Physically carnelian stimulates the absorption of vitamins, nutrients and minerals in the small intestine, thereby improving the quality of the blood. It ensures a good blood supply to the organs and tissues. A stone of both fertility and male potency, carnelian can relieve PMS and menopausal symptoms. Wearing a carnelian relieves addictions of all kinds, especially problems centring on food that may be linked with low self-esteem. Carnelian alleviates rheumatism and stimulates the metabolism. 
Cleanse carnelian with sunlight or under running water. Keep carnelian with other stones to cleanse them of negative energies.