All About Agate
There are so many kinds of agate, many with very long histories of use. Agate is a type of microcrystalline quartz called "chalcedony." (Pronounced "kal-sed-oh-nee") Microcrystalline means that while the quartz has crystallized, it has done so on a microscopic scale, so this mass of quartz crystals just looks like one amorphous blob of rock. Aventurine is also a form of microcrystalline quartz, but it has metallic particles mixed in, giving it a glittery appearance. Jasper is also closely related, but tends to have so much mineral inclusion as to be totally opaque while all of the above stones are at least slightly translucent or milky in appearance.
The difference between agate and regular chalcedony is that the stones we call chalcedony tend to be one colour. IF they are multiple colours, those colours gently fade into each other like watercolour. Agate is multiple colours, usually in bands, created from different layers of chalcedony layering over top of each other over time. This actually makes agate and onyx closely related. The difference here is that onyx has fairly even, parallel banding, while agate can have all sorts of fun shapes and bands of colour may swirl or be otherwise short or uneven. Sometimes stones we call agate (like Moss Agate) are technically one of the other above varieties. Another feature of agate is that while it is microcrystalline, larger quartz crystals can often be found mixed in, especially in agate geodes.
Agate has such a long history of use by humans that polished agate beads have been discovered in the Indus Valley region dating back four thousand years. Agate is named for the Achates river, where the ancient Greeks first discovered it for themselves. It was a popular material for hard stone carvings and was often used for wax seals. (Carnelian, a type of red agate, was particularly popular for this.) Agate is quite hard (7 on Mohs scale), keeps its polish fairly well, and is resistant to most chemicals. For this reason, it has long been used for tableware and mortar and pestles, and is still used in certain laboratory tools.
When it comes to the general energy of agates, they are thought to help with clarity and focus. They are a stone associated with truth and courage, as well as healing and longevity and with the soothing of a troubled mind. Agates are generally associated with the planet Mercury, the sign of Gemini, and the element of air. They are also associated with the deity Aesculapius. They are sometimes associated with the Fool or the Magician card in tarot.
There are innumerable varieties of colours and patterns of agate, but here are some of the named varieties:
Agatized Fossils are fossils in which the rock that filled the fossil cavities is agate. It is a very common form of fossilization. Most ammonite fossils and petrified woods are agatized. These carry specifically the energy of whatever the kind of fossil is.
Banded Agate possesses alternating bands of dark and light colour and is one of the most common forms of agate. In my experience, the light bands are often more opaque than the dark bands, and it is not uncommon to find quartz crystals at the centre or between certain bands. Banded agate is considered protective, especially from stress, and is sometimes associated with fire (esp when of a warm hue).
Black Agate closely resembles black onyx. The main difference is that it presents uneven or winding lines instead of straight, even lines. It also generally has a glassy lustre where onyx generally has a waxy lustre, though this is not 100% true all the time. Black agate is also considered protective and connected to fire, and it is also thought to help with success.
Blue Agate is often actually a dyed agate. You can tell if blue agate is dyed by if all the bands of colour are within the same hue. In my experience, most natural blue agates appear grey or black until a light is shone through them. These agates are soothing and pacifying and associated with water.
Botswana Agate can be recognized from other grey agates by the fact that its grey slightly hued pink or violet. It is thought to protect from manipulation and to help ease addiction. It is connected to water.
Brown or Tawny Agates are thought to be a stone of warriors, ensuring success in whatever battles one may face. Thought to protect against the Evil Eye and to also be connected to the element of fire.
Carnelian is a form of Red Agate. Technically, all red agates are carnelian, but in general the name "carnelian" is reserved for slightly translucent red-orange agates with white or beige banding. Much darker colours tend to be called Blood Agate, and everything else is that is red-dominant and an agate (and is not one of the other pattern varieties) is simply Red Agate. All three of these types are thought connected to blood, the heart, and human health, as well as passion and fertility. They are generally connected to the element of fire.
Enhydro Agate is a type of agate (usually a geode) which contains an amount of trapped water inside. It is thought to be soothing and connected to the element of water.
Fire Agate is a yellow-brown agate that forms in concentric spheres. The specific manner in which it forms causes slight iridescence when broken open properly. It is connected to inspiration and the element of fire.
Green Agate is often a form of dyed agate. To tell real green agate, it should not be a lurid shade and the different bands of colour should not all be in the same hue spectrum. Green agate is thought to help with healing and is connected to the element of earth.
Iris Agate is a type of greyish, translucent agate that, when sliced thinly and has a bright light shone through it from the other side, displays a rainbow of beautiful colours. It is connected to the mysteries of creation and to the element of air.
Lace Agates have a "lacy" appearance due to a high amount of intricate swirls and dots. Blue Lace Agate is only in shades of pale blue, pale grey, and white. It is thought to bring peaceful contentment and to help one de-stress. It is connected to the element water. Meanwhile, Crazy Lace Agate is primarily red and white but can also feature yellows and greys. It is thought to help stabilize scattered thoughts and is associated with the element of earth.
Moss Agate is not a true agate, depending on definition, but a form of dendritic chalcedony. There is a lot of debate about what is Moss Agate, what is Tree Agate, and what is Dendritic Agate, but there is a long history of these names being used interchangeably. Today, the general consensus (though there are still many other opinions) seems to be that Moss Agate should have green or brownish-green parts which look fairly similar to moss, Dendritic Agate should be very translucent with well-defined "leaves" or "dendrites," and Tree Agate is much more heavily dominated with green than with other colours. All three are thought to improve health, particularly the health of plants, and to exhibit the elemental power of earth.
Picture Agate is a type of agate which seems to exhibit naturalistic pictures, often including dendrite “trees.” It has a similar energy to Moss Agate, mentioned above.
Pink Agate, also called Pink Carnelian, is an incredibly loving stone and helps one look past their differences with another person. It is connected to the element of air.
Plume Agate has bands of colour which have swirled together in a way that resembles plumes of smoke or feathers. It comes in a number of varieties which are named for where they are found (such as Bloody Basin) or their appearance (such as Flame Plume). These are thought to help with motivation and to be connected to the element of fire.
Polyhedral Agate is a type of agate that happens to form with flat sides such that its bands form shapes similar to polyhedrons. These are thought to enhance one’s thinking and connect one to other realms. These are connected to the element of air.
Sagenic Agate has other crystals embedded in it, such as rutile needles or quartz crystals. Any other pattern of agate can also be sagenic. These agates are thought to contain the compounded wisdom of multiple stones.
Tube Agate either actually has little tubes running through it or features streaks that look like interconnected tubes. It is often found with certain Moss Agates. It is thought to aid communication and to be connected to the element of water.
Turritella agate is a type of agatized fossil that is often treated as an agate pattern. It contains small agatized fossils of Turritella sp. surrounded by more agate or chalcedony. It is thought to have the energy of the sea and to connect to previous lives and one’s ancestry, and is connected to the element of water.