For the Rock hounds in our group:
The agate must be cut and polished to bring out its beauty and hidden pattern. There are hundreds of Agate types and names. Below is a list we acquired, citing the well-known and commonly used variety names. Many stones are referred to as agates, however if they lack banding, they may be a variety of Chalcedony, but they are not true agates.

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.
Brecciate Agate - Agate with broken fragments naturally cemented together.
Cloud Agate - Grayish Agate with blurry, foggy patches of inclusions.
Crazy Lace Agate - Agate composed of twisting and turning bands of various colors.
Dendritic Agate - Chalcedony with tree-like or fern-like inclusions.
Enhydro Agate - Agate nodule 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 rings.
Fairburn Agate - Beautiful, unique, and rare Fortification Agate from Fairburn, South Dakota.
Fire Agate - Agate with Goethite or Limonite inclusions, which cause the stone to be iridescent.
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 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 of green Hornblende.
Nipomo Agate - Agate with Marcasite inclusions found in Nipomo, California.
Onyx - 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 in feather-like patterns.
Pom Pom Agate - Agate with yellow inclusions resembling pom poms.
Pseudo Agate - Agate as a replacement of organic material.
Rainbow Agate - Iridescent Agate exhibiting all colors of the spectrum when sliced in thin slabs.
Sardonyx - Agate with straight parallel bands of brownish to red alternating with white or black bands.
Sagenite Agate - Clear Chalcedony containing inclusions of other minerals.
Scenic Agate - Chalcedony with tree-like designs closely resembling scenery.
Snakeskin Agate - Reddish brown Agate with black concentric bands.
Star Agate - Agate with banding lines in the formation of a star.
Sweetwater Agate - Chalcedony with star-shaped patterns of manganese oxide inclusions, found in the Sweetwater River, Wyoming.
Thunder Egg - Nodule filled with Agate in the center.
Tube Agate - Agate with tube-like formations which are sometimes hollow.

The science of the Agate
Chalcedony is a microcrystalline variety of Quartz, mineral 75.1.4.1vr. Whose chemical composition is silicon dioxide. It is banded, occurring in a variety of color combinations. There are literally thousands of localities where fine specimens have come. Only a select few are mentioned here. The first worked Agate deposits were near Idar-Oberstien, Germany, where Agate Geodes of unique habit were found. That deposit has long since been worked out. The most abundant source of Agate Geodes is the Rio Grande do Sul in Brazil, where many different sizes and types occur. These Agates are easily dyed. An interesting Agate Geode type, known as a "Thunder Egg" can be found in large amounts in Jefferson Co., Oregon. Commercial Agate deposits also exist in China, India, Madagascar, Mexico, and on the shores of Lake Superior. "Fire Agate" comes from Mexico and Deer Hill, Arizona

Metaphysical Properties of Agate
Agate comes in reds, browns, yellows, oranges, and blacks, sometimes with banding, stripes or zoning. Agate is good protective stone, especially for children. It also can help strengthen the body and the body's connection to the earth. It can lessen feelings of envy by grounding the emotions.  Agate balances the physical, emotional and intellectual bodies, and balances and cleanses aura.  Agate is known to stimulate analytical abilities and perception, while eliminating negativity. It has also been reported to strengthen sight and promote marital fidelity.

Agate is a banded, concentric shell-like chalcedony, sometimes containing opal substance.  The fine quartz fibers are oriented vertically to the surface of the individual band layers.  The bands can be multicolored or of the same color.  South American Agate is mostly dull gray and without special markings; only through dyeing do they receive their lively colors.  Transparency of Agates varies from nearly transparent to opaque.  In thin slabs, even the opaque Agates are mostly translucent.  The name Agate is supposedly derived from the river Achates (now called the Drillo) in Sicily.  It overcomes bitterness of the heart and eliminates inner anger.

Agate fosters love, opening the way for positive relationships!