Lace agate is a variety that exhibits a lace-like pattern with forms such as eyes, swirls, bands or zigzags.
Blue lace agate is found in Africa and is especially hard.
Crazy lace agate, typically found in Mexico, is often brightly colored with a complex pattern, demonstrating randomized distribution of contour lines and circular droplets, scattered throughout the rock.
The stone is typically coloured red and white but is also seen to exhibit yellow and grey combinations as well.

Moss agate, as the name suggests, exhibits a moss like pattern and is of a greenish colour.
The coloration is not created by any vegetative growth, but rather through the mixture of chalcedony and oxidized iron hornblende.
Dendritic agate also displays vegetative features, including fern-like patterns formed due to the presence of manganese and iron oxides.

Turritella agate (Elimia tenera) is formed from the shells of fossilized freshwater Turritellas, gastropods with elongated spiral shells.
Similarly, coral, petrified wood, porous rocks and other organic remains can also form agate.

Coldwater agates, such as the Lake Michigan Cloud Agate, did not form under volcanic processes, but instead formed within the limestone and dolomite strata of marine origin.
Like volcanic-origin agates, Coldwater agates formed from silica gels that lined pockets and seams within the bedrock.
These agates are typically less colorful, with banded lines of grey and white chalcedony.

Greek agate is a name given to pale white to tan colored agate found in Sicily, once a Greek colony, back to 400 BC.
The Greeks used it for making jewelry and beads.

Brazilian agate is found as sizable geodes of layered nodules.
These occur in brownish tones inter-layered with white and gray.
Quartz forms within these nodules, creating a striking specimen when cut opposite the layered growth axis.
It is often dyed in various colors for ornamental purposes.

Polyhedroid agate forms in a flat-sided shape similar to a polyhedron.
When sliced, it often shows a characteristic layering of concentric polygons.
It has been suggested that growth is not crystallographically controlled but is due to the filling-in of spaces between pre-existing crystals which have since dissolved.

Other forms of agate include Holley blue agate (also spelled "Holly blue agate"), a rare dark blue ribbon agate only found near Holley, Oregon; Lake Superior agate; Carnelian agate (has reddish hues); Botswana agate; Plume agate; Condor agate; Tube agate containing visible flow channels or pinhole-sized "tubes"; Fortification agate with contrasting concentric banding reminiscent of defensive ditches and walls around ancient forts; Binghamite, a variety found only on the Cuyuna iron range (near Crosby) in Crow Wing County, Minnesota; Fire agate showing an iridescent, internal flash or "fire", the result of a layer of clear agate over a layer of hydrothermally deposited hematite; Patuxent River stone, a red and yellow form of agate only found in Maryland; Enhydro agate contains tiny inclusions of water, sometimes with air bubbles.
Lace agate is a variety that exhibits a lace-like pattern with forms such as eyes, swirls, bands or zigzags. Blue lace agate is found in Africa and is especially hard. Crazy lace agate, typically found in Mexico, is often brightly colored with a complex pattern, demonstrating randomized distribution of contour lines and circular droplets, scattered throughout the rock. The stone is typically coloured red and white but is also seen to exhibit yellow and grey combinations as well.
Moss agate, as the name suggests, exhibits a moss like pattern and is of a greenish colour. The coloration is not created by any vegetative growth, but rather through the mixture of chalcedony and oxidized iron hornblende. Dendritic agate also displays vegetative features, including fern-like patterns formed due to the presence of manganese and iron oxides.
Turritella agate (Elimia tenera) is formed from the shells of fossilized freshwater Turritellas, gastropods with elongated spiral shells. Similarly, coral, petrified wood, porous rocks and other organic remains can also form agate.
Coldwater agates, such as the Lake Michigan Cloud Agate, did not form under volcanic processes, but instead formed within the limestone and dolomite strata of marine origin. Like volcanic-origin agates, Coldwater agates formed from silica gels that lined pockets and seams within the bedrock. These agates are typically less colorful, with banded lines of grey and white chalcedony.
Greek agate is a name given to pale white to tan colored agate found in Sicily, once a Greek colony, back to 400 BC. The Greeks used it for making jewelry and beads.
Brazilian agate is found as sizable geodes of layered nodules. These occur in brownish tones inter-layered with white and gray. Quartz forms within these nodules, creating a striking specimen when cut opposite the layered growth axis. It is often dyed in various colors for ornamental purposes.
Polyhedroid agate forms in a flat-sided shape similar to a polyhedron. When sliced, it often shows a characteristic layering of concentric polygons. It has been suggested that growth is not crystallographically controlled but is due to the filling-in of spaces between pre-existing crystals which have since dissolved.
Other forms of agate include Holley blue agate (also spelled "Holly blue agate"), a rare dark blue ribbon agate only found near Holley, Oregon; Lake Superior agate; Carnelian agate (has reddish hues); Botswana agate; Plume agate; Condor agate; Tube agate containing visible flow channels or pinhole-sized "tubes"; Fortification agate with contrasting concentric banding reminiscent of defensive ditches and walls around ancient forts; Binghamite, a variety found only on the Cuyuna iron range (near Crosby) in Crow Wing County, Minnesota; Fire agate showing an iridescent, internal flash or "fire", the result of a layer of clear agate over a layer of hydrothermally deposited hematite; Patuxent River stone, a red and yellow form of agate only found in Maryland; Enhydro agate contains tiny inclusions of water, sometimes with air bubbles.
Agate