Banded Agate

Also known as Water Line Agate. This type of formation forms a layered pattern. I explain to people as if you have a stack of paper.

Text book says: Agate with colors usually disposed in parallel bands, which are more or less wavy. 

Fortification Agate

Text book terms says: Agate with parallel zig zag lines.

Also known as Topographic Agate - Agate with fine markings like lines on a topographic map.

Drusy Quartz

Usually hollow pockets covered with minute crystals. Typically drusy will have a high "sparkle" to it caused by light reflecting off the individual quartz points. Some people compare to this as a texture like fine sugar crystals.

Botryoidal Agate

"Botryoidal" - is a texture which form resembles a bunch of grapes

Plume Agate

Also known as Flower Agate. Contains inclusions of minerals arranged in flowerlike forms.

Sagenite Agate

Sagenite in another variety of internal growth. Sagenites are typically a needle like structure. They can also form as bursts of needles.

Moss Agate

"Moss" - is another form of interior inclusions. These form random shaped forms from small tubes, to thick bush type structures.

"Tilt"

A "tilt" as you can seen in the photo, is a uneven band formation. In theory during formation a ground movement (earthquake, slide etc..) has moved the specimen and changed it's banding layers to a different degree.

Negative Crystal Cast

 This is where a internal crystal once grew. Over time the crystal has broken or disolved from the core leaving a hollow void in the shape of the crystal structure.

Brecciated

Rock composed of angular fragments held together in matrix.

"Egg in Egg"

Speaks for itself. These are Thundereggs which form inside Thundereggs. As my photo shows, the specimen contains an Egg inside an Egg inside an Egg.

Triconoid Core

This is a Thunderegg core which forms a 3 point core structure.

Biconoid Core

Often refered to as UFO Core these look like small flying saucers. Other text books have described an example as two Chinese Coolie Hats together.

Slip Egg

Another one of Mother Natures Rarities. During a freak formation these Thundereggs have fractured and slid apart, the re-glued themselves together.