The TOPS A Rock Shop Rock of the Month for June 2013 are those Astonishing Agates!! These amazingly colorful stones are found throughout the world and in a rainbow of colors. Agates are a microcrystalline form of silica, primarily chalcedony. Known for the striking bands that are visible in the stones, agates are fine grained. Because they are fine grained, agates take a polish well and since they are a relatively hard stone (7 – 7.5 on the Mohs scale) they are often used in jewelry and carvings.
Agates are formed in various ways. Volcanic or metamorphic activity can leave bubbles, cracks or cavities in the base rock. Over time silica builds up in layers on the walls of the cavities, most likely through water seeping through cracks in the stone. The layering creates the banding that is associated with agates. When a cavity or crack is not completely filled, it is often coated with crystals. This fine layer of crystals is commonly known as drusy.
Areas famous for their agates include Brazil, China, USA, India, Egypt, Australia and Mexico. The Chinese have been mining and using agates for over 8000 years with the provinces of Heilongjiang, Liaoning, Inner Mongolia and Hubei being significant production areas. Recent discoveries of large agate fields have made agate, a highly valued gemstone in Asia, more affordable to the consumer.
As with all gemstones, agate has certain characteristics that determines the value of one agate as compared to another agate. The color of agate should be clean and bright with the color layers thin. The more transparency the agate displays, the higher the value of the agate. Also, the shape and pattern should be clear and easy to see.
So what makes it an agate versus chalcedony or jasper? Agate has veins while chalcedony has is smooth in color. Jasper usually has impurities or is mixed with clay providing less transparency and less shine.
Agate lore dates back centuries! Agate was considered valuable as a talisman or amulet. It was thought to protect from fever and thirst. Legends indicated that the ancient Persians thought agate could divert storms. Today people use agate for balance the body, mind and spirit. It is believe to augment you mental capacities and bring inner calm.