1st-2nd century AD Roman carnelian intaglio ring stone with Capricorn insignia. Item for sale at Vilmar Numismatics: http://vilmarnumismatics.com/
Carnelian is a stone that we have all probably seen, but we rarely identify it by name or give it much thought.
Carnelian is a form of chalcedony quartz (SiO2) with rust (iron oxide) impurities that give it a distinctive ruddy color. It has been used worldwide for centuries for adornment and as a symbol of the noble class. The Romans used it extensively to make signet rings, as hot wax did not adhere to the stone and it took well to carving. The ancient Greeks and Babylonians believed the gem brought good luck and protection from natural disasters. Napoleon wore a carnelian seal he found in Egypt, and the ancient Egyptians were fond of placing carnelian talismans on and around their mummies for ensuring safe passage to the afterlife. The humble stone we pass over today used to command much more attention, and it can make quite a statement in bold settings.
Turkomen gold and silver headdress with carnelian from Central Asia. Image from the Ringling Museum of Art, previously displayed at http://mcclungmuseum.utk.edu/exhibits/splendid-treasures/
Carnelian is found all over the world, with large deposits in India, Brazil, and the Middle East. There are isolated places in the New England states where you can gather carnelian from riverbeds and streams, and my friend has some that I am looking forward to polishing. It should be noted that the vast majority of carnelian on the market is dyed and heated agate, which while carnelian is a form of agate, it has a specific appearance. Still, at 7 on the Mohs scale, it is durable and a good all-purpose jewelry stone.
Carnelian is thought to sharpen concentration and protect its wearer from harm, as well as grant eloquent speech.