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Agate Types


Agate is a banded [1], multicolored, variety of Chalcedony [2]. It occurs in an infinite amount of colors and patterns, and no two Agates are alike. The extraordinary beauty and uniqueness of Agate is responsible for its great popularity.

Agate must be polished to bring out its full charm; unpolished specimens are dull and ugly. It usually forms in rounded nodules or knobs which must be sliced open to bring out the internal pattern hidden in the stone.

Literally hundreds of Agate types were coined with special variety names. Most of these are hardly known, and new ones are made up every year. Most of these names have no scientific support, and it is not in the scope of this guide to list all variety names. The list below cites only the well-known and commonly used variety names.

Some varieties have two names which are equally used. Don't be surprised when you see the same definition for two different variety names. You will notice by some varieties that the word Chalcedony is used in the definition, instead of Agate (as is the case in Dendritic Agate). This is NOT a mistake. These "varieties" are not really Agates, as they lack banding, and, although they have the word agate in their name, are only a variety of Chalcedony.

Blue Lace Agate
- Agate with light blue bands in a lacy or wavy pattern.

Botswana Agate - Agate from Botswana banded with fine, parallel lines, often with a preponderance of pink blending into white.

Brecciated Agate - Agate with broken fragments naturally cemented together.

Cloud Agate - Grayish Agate with blurry, foggy patches of inclusions [3].

Crazy Lace Agate - Agate composed of twisting and turning bands of various colors.

Dendritic Agate - Chalcedony with tree-like or fern-like inclusions [3].

Enhydro Agate - Agate nodule [4] partly filled with water. The water can be seen from the outside of the nodule when held up to the light. Also known as Enhydritic Agate.

Eye Agate - Agate with banded, concentric [5] rings.

Fairburn Agate - Beautiful, unique, and rare Fortification Agate from Fairburn, South Dakota.

Fire Agate - Agate with Goethite or Limonite inclusions [3], which cause the stone to be iridescent [6].

Fortification Agate - Agate with a pattern resembling a medieval fortress (i.e. imaginary moat and castle walls can be perceived).

Fossil Agate - Agate as a replacement of organic material.

Iris Agate - Iridescent [6] Agate exhibiting all colors of the spectrum when sliced in thin slabs.

Laguna Agate - Beautiful and colorful type of Agate from Ojo Laguna, Chihuahua, Mexico.

Landscape Agate - Chalcedony with tree-like designs closely resembling scenery.

Mexican Lace Agate - Agate consisting of thin bands in a lacy or wavy pattern.

Moss Agate - Chalcedony with dense inclusions [3] of green Hornblende.

Nipomo Agate - Agate with Marcasite inclusions [3] found in Nipomo, California.

Onyx [7] - Agate where the banding lines are straight and parallel, and consistent in band size.

Oregon Snakeskin Agate - White to cream Chalcedony with a wrinkled or cracked "skin", found in Oregon.

Plume Agate - Agate with inclusions [3] in feather-like patterns.

Pom Pom Agate - Agate with yellow inclusions [3] resembling pom poms.

Pseudo Agate - Agate as a replacement of organic material.

Rainbow Agate - Iridescent [6] Agate exhibiting all colors of the spectrum when sliced in thin slabs.

Sardonyx [8] - Agate with straight parallel bands of brownish to red alternating with white or black bands.

Sagenite Agate - Clear Chalcedony containing inclusions [3] of other minerals.

Scenic Agate - Chalcedony with tree-like designs closely resembling scenery.

Snakeskin Agate - Reddish brown Agate with black concentric [4] bands.

Star Agate - Agate with banding lines in the formation of a star.

Sweetwater Agate - Chalcedony with star-shaped patterns of manganese oxide inclusions [3], found in the Sweetwater River, Wyoming.

Thunder Egg - Nodule [4] filled with Agate in the center.

Tube Agate - Agate with tube-like formations which are sometimes hollow.



[1] Banded - Forming "bands" of different colors. See banding. Also refers to wavy bands of veins in surrounding rock.

[2] Chalcedony - Microcrystalline variety of Quartz.

[3] Inclusion - Materials that are locked inside a mineral as it is forming.

[4] Nodule - Aggregate consisting of a spherical lump, usually from groups of small crystals.

[5] Concentric - Aggregate describing foliated masses that are somewhat spherical and rotate about a center; appearing like a rose (rosette). Also used to describe a form of banding where the bands are circular, forming rings about a central point.

[6] Iridescent - Exhibiting iridescence.

[7] Onyx - Onyx is a variety of Agate where the banding lines are straight and parallel, and consistent in band size. Onyx usually refers to material with alternating bands of black and white, but other color combinations exist. Onyx is the name given to Agate of this habit, although banded Calcite or Aragonite of this type may also be called Onyx. The name Onyx may also incorrectly refer to unbanded, solid Chalcedony dyed black. Onyx is carved into ornamental figures, cameos, beads, and cabochons.

[8] Sardonyx - Sardonyx is a variety of Agate where the banding lines are straight and parallel, and consistent in band size. The color of the bands are brown to red, and alternate with white or black bands. Sardonyx is a type of Onyx in which the color of the bandings is defined. In the gem trade, Carnelian is often incorrectly called Sardonyx. Sardonyx is carved into ornamental figures, cameos, beads, and cabochons.

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