You probably think… what kind of a statement is this? ‘Do you know that this exceptional gemstone can be crazy and on fire?’. Well, it is a funny question but it is true. I don’t know of another gemstone with so many varieties and therefore names, than this gem. What do you think about crazy lace-, fire-, Botswana-, Condor-, Brasil-, flower agate, and so on?
You wonder are those varieties all agates? Why are there so many types? How can you recognize them all? What the h… is it anyway?
Well, let’s start by giving you the answers. That’s what I am here for. And by the end of this blog, you appreciate and love this beautiful gemstone even more than you do now.
What is this gem, besides a gemstone?
Agate is a rock formation, made of quartz, chalcedony, and silica. It occurs in many colors, but not so much in blue and green. And this beautiful gem is made in volcanic cavities. The gem’s minerals like to form an agate gemstone on another rock in those cavities.
When a volcano explodes gasses and fluids come out. The gasses make cavities when they are trapped in the fluid volcanic material. And the fluids, full of silica, fill up the cavities. Imagine you stand on the beach and the water comes in and flushes away again. Well, the silica-rich fluids come into the cavity and deposit their first layer. The second fluid wave comes in with a little different amount of silica and some other minerals. The result is that the second layer has a different color than the first one and the border between the two layers forms a ‘band’.
Those layers consist of silica, quartz, and chalcedony. And sometimes there is not enough space in the cavity and in the layers of the gemstone the quartz is formed.
What about the different colors?
The different colors come from the different minerals that are present in the fluids that enter the cavity or vesicle.
The first layer is mostly green and when a fluid with iron oxide forms the second layer the color turns brownish or rusty. But also manganese, nickel, chromium, or even titanium cause of all kinds of different colors.
And sometimes when the agate is formed in the sedimentary rock you find little branches, leaves, or other organic material in the stone, giving it a different color, but also a different design.
The agate itself, like a rock, is not so special. The beautiful colors and designs come forward when the stones are cut and polished. When you want to purchase a piece of jewelry with this gem you pay more when the stone had vivid and natural colors than when the colors are less intense or even artificially dyed.
The color blue and green in this stone are least common, so you pay more for stones with these colors, than for gems with red or yellow colors.
Most of these gemstones are translucent, with a few transparent or opaque exceptions. If you want to purchase this gemstone it should be eye-clean, which means that there should not be any visible large inclusions or fractures in the stone.
Like everything, there are some exceptions, and you will find them with the moss, dendritic and plume agates. In these exceptions, the inclusions and fractures form the pattern of the stone and make them extra special, and of course more expensive.
And the cut
Agates are a real challenge for a stone cutter. Of course, he or she wants the beautiful bands and patterns of this gem to make them look as good as possible. FlorenceJewelshop has necklaces made of this gemstone in her collection of which every bead is different; with different bands and patterns.
And this ‘play of color and pattern’ makes the agate so special. Not only beads are individually cut, but also the cabochons for rings and pendants (or ‘framed’ necklaces). And carved statues or sculpted pieces are coming to life when the cutter is experienced and talented.
The price of the agate is not set because the material is expensive, but the price depends on the artistry and the skill of the cutter. And who the patterns and colors of the stone come forward.
As stated above you can recognize the agate by her bands. And there are two characteristic types of them:
The Wall-lining banding. The bands run straight or perpendicular to the growth direction of the Chalcedony fibers, which go from the sides to the interior of a cavity. To say it more simple: you get a pattern that looks like an onion. You see this type of banding in the walls of geodes and around structures that grew into the cavity, like crystals or inclusions.
The horizontal banding. (or the Uruguay-type banding). This type of banding is not very common. The bands look like small but irregular spaced layers of chalcedony in the cavity. And they are horizontal. What is striking in this type of banding is that the difference between the layers is pronounced in color and translucency. This banding type is used to make cameos and engravings.
Don’t think that every banded chalcedony is an agate. There are varieties of chalcedony with bands, but which are no agates, like banded flint.
Where is the name coming from?
Although the agate stone is much older the first one to recognize its beauty of it is the Greek philosopher Theophrastus. He discovers the stone in the 3rd or 4th centuries BC on the shores of the Achates River in Sicily.
Above I stated that this stone was much older, and that is an understatement. Archeologists find out that this gem is used as a decorative stone for more than 22.000 to 18.000 years. Grave finds proved that people knew this gemstone since the Bronze Age (5.000 years ago) in Western Europe. And from 400 BC the Greeks made beaded jewelry and signet rings out of agate.
Since that time and since people know how to polish the stones, people use them for jewelry and as the basis of carved items (as decoration) and beads.
There is a story that a rich king in the Middle East uses tiles of this beautiful shiny gem to cover the floor of the meeting room of his palace. Workmen polish the stone until it looks like a mirror. And the king can look under the skirts of the female guests, just to make sure that they are female and no covered-up male spies. The story says that the king was king Salomon who got Queen Sheba as a visitor!
Every color & every design form another variety.
There are so many different colors and designs that people give them a different name to distinguish them from other types of this gem. Just to mention a few…
(Crazy) lace agate
has a very complex design and when you look at it closer you get ‘crazy’ of all the stripes, swirls, bands, and lines. You find the ‘crazy variety’ mostly in Mexico and the colors are red and white. Sometimes you see yellow and gray variations of the craze lace type. The pattern is very complex (crazy) with a demonstrating randomized distribution of contour lines and round droplets.
There is also a blue lace variety, that is found in Africa. It’s very hard, mostly blueish, and also has a lot of ‘zigzags’ and ‘lines’.
is of course green and has a pattern that looks like moss. Although there is no moss inside or any other natural vegetation. The green color is ‘made’ by the minerals chalcedony and rusty iron hornblende.
There is a dendritic variety that looks as if there is some green vegetation hidden in the gemstone. The fern-like patterns of this variety are formed by the manganese and iron oxides.
is one of my favorites. You find them in all sorts of colors and you see an iridescent internal ‘fire’ in the stone. That fire is the combination of clear copies and hydrothermally deposited hematite.
are completely different since they are not formed by volcanic action. For example, Lake Michigan Cloud- and the Lake Superior agate are formed in limestone and dolomite layers and have a marine origin. The colors are less specific and vivid and the bands are white and gray (Chalcedony).
Another variety that has a marine origin is the turritella agate, which is formed by shells of fossilized Turritella shells, that have a spiral shape. Also, coral, petrified wood, and other organic remains can be formed into agate.
is found only in Botswana and has typical bands and sometimes you find a ‘drusy’ of quartz in the vesicles of this gem type.
is a pale white to tan-colored variety found in Sicily, which once was a Greek colony (in 400 BC). This stone is very popular to make jewelry, especially beaded jewelry.
There are many more, but these ones are the most commonly used in pieces of jewelry. Like the Holley or Holly Blue variety, which has a rare blue ribbon and only can be found near Lake Superior in Orgon. Or the carnelian type with reddish hues, the plume- and the Condor agate, Binghamite (only found in Minnesota), and many more.
An overview of the agate varieties:
|Agate-Jasper||A variety that includes jasper and veins of chalcedony||Iran|
|Agatized coral||A variety that replaces the coral into chalcedony||Florida USA|
|Bird’s eye||The ‘eyes’ in the gemstone looks like the eyes of a bird||Mexico|
|Blue lace||A pale blue variety with bands||Namibia|
|Botswana||With fine banded paralel lines, often colored pink and white with gray||Botswana. Africa|
|Brecciated||Sedimenatry mixture of broke agate fragments||Wyoming USA|
|Clouded||Gray colored variety with blurry foggy-type inclusions||Wyoming USA|
|Crazy lace||Variety with multicolored twisting, zigzag and turning patterns||Arizona, Mexico, Namibia|
|Enhydro||A gem nodule that is partly filled with water||Brasil, Indonesia, Oregon USA|
|Eye||Variety with a concentric ring pattern, that looks like an eye||Botswana|
|Fairburn||Rare variety found in Fairburn||South Dakota, USA|
|Fortification||Variety with sharp-angled bands that look like a castle (Fairburn is example)||USA|
|Fire||Colorful variety with ‘water’ inside||Mexico|
|Fossil||Agate is the replacement material in fossils (see also the agatized coral)||USA|
|Haema-ovoid||Reddish variety with oval patches||Wyoming USA|
|Iris||Variety of which sliced in thin layers it has all the colors of the spectrum||Brasil, USA|
|Laguna||Colorful variety||Ojo Laguna Chihuahua Mexico|
|Lake Superior||the oldest variety of more than 1 billion years old, pale colored||North USA|
|Mexian lace||lacy or wavy variety||Mexico|
|Mocha||variety that has inclusions of pyrolusite||Saudi Arabia|
|Moss||green variety||India, Scotland, USA|
|Onyx||black and white banded variety||Greece, Yemen, Uruguay, Argentina, Australia, Brazil, Canada, China, Czech Republic, Germany|
|Pigeon||blood-red and white variety||Utah, USA|
|Riband||banded variety||Brasil, Uruguay, Madagaskar, Mexico, USA|
|Sardonyx||variety with reddish to brown or black and white bands||Brazil, India, Germany, Uruguay, Russia, USA|
|Youngite||variety coated with druzy quartz crystals||Wyoming, USA|
Use of agate
You won’t expect it probably, but this gemstone is used quite often in industry, because of its features, like its resistance to chemicals and its hardness (6.5-7 on the scale of Moh). They make bearings for laboratory balances and precision pendulums of this stone. Or mortars and pestles or for leather burnishing tools.
But most of this gemstone is used to make pieces of jewelry out of it. One of the most important centers was Idar-Oberstein in Germany, where they found agates initially, but the mines got exhausted. Then they shipped the stone as ballast from Brasil and specialized in making beads.
Not only beads but also the six windows of the Presbyterian Church in Yachats (Oregon, USA) were made of agates, that were found on the shores of the beach.
Back to Idar-Oberstein where they more or less invented the dying of the agates. Being a family of the chalcedony and knowing that the chalcedony is rather porous, you don’t have to wait long, before they started dying the gemstone. And there was a reason for doing it.
Since the mines were exhausted in Idar-Oberstein, I told you that they got agates from Brasil to make sure that their gemstone industry did not collapse. The only disadvantage was that the Brazilians send gray agates to Germany, instead of the colorful ones, they were used to. They could not solve the matter, only with dying the stones, with extraordinary results.
Interested in gemstones? I wrote a practical PDF where you can find all the information about birthstones and other gemstones, like this gemstone, in one handy overview. It is free! Just let me know where to send it to:
Hug, Florence of FlorenceJewelshop