Gem Profile- Moss Agate and Plume Agate

by Judy Ellis

Just as there are many kinds of included quartz, there are several varieties of included agate. Sagenite agate, or sagenitic agate, has needlelike inclusions in a sunburst or fan shape, and come in a variety of colors.

Dendritic agate, such as Montana agate, has thin, dark inclusions that resemble trees or branches.

Plume agate features featherlike inclusions that look like smoke, clouds, or feathers.

Moss agate appears like green moss, seaweed, or even blue cheese on a translucent background. It is the most common and well-known included agate for jewelry makers.

Frances Lediaev wire-wrapped this beautiful moss agate cabochon.

Some rockhounds don't consider included agates to be true agates because they lack the concentric banding typical of most agates, formed in gradually larger circles around a center point.

However, they are part of the quartz-chalcedony-agate family of silica minerals, formed from silicon dioxide.

Montana agate and Plume agate are among the top-tier agates for jewelry making, surpassed only by rare stones like fire agate.

Moss Agate

Moss agate is usually green with pale to translucent patches.

Tree agate also has green, moss-like inclusions but features white opaque patches instead of translucent areas.

A moss agate cabochon (left) and a tree agate cabochon (right) are essentially the same.

The difference is that tree agate has opaque white patches, while moss agate is translucent with similar green, moss-like inclusions.

Judy Copeland wire wrapped this moss agate in silver craft wire. The design in the stone looked to Judy like a rainstorm with lighting! It is hung on a base metal Viking weave necklace.

Montana moss agate is unique because it originally formed in the volcanic region of Yellowstone National Park.

Today, it can be found in the gravel of the Yellowstone River in Montana. It typically features large red (iron oxide) and black (manganese oxide) inclusions on a translucent background.

Judi Hogan wire-wrapped this Montana moss agate in an angular cabochon pendant frame.

Plume Agate

Plume agate gets its name from the fluffy, feather-like shapes in its patterns.

There are several types of plume agate, including Priday, Graveyard Point, Del Norte, West Texas, and Mexican Plume. The example shown here is from Texas. I have a Texas plume agate cabochon with the same gold, orange, green, and white colors.

This Graveyard Point plume agate slab comes from Dorothy Duflo. On the left, it is shown on a background, and on the right, held to the sun.

Dorothy is wondering what to make with it what do you think of using it for a belt buckle?

In Tucson, I saw Graveyard Point Plume Agate for the first time: this distinctive golden, tan, white, and gray-blue (and sometimes pink) agate is named for the stone's location, found in the Owyhee Mountains along the Idaho-Oregon border, near the burial place of an 18th century massacre.

I found this tub of graveyard point plume agate slices, ready to be cut into cabs, at the RV Park Show near the TEP Show in Tucson 2012 with a closeup of the same graveyard point plume agate slices, sparkling wet in the Arizona sun.

Priday plume agate is another variety you might encounter. It was a rare plume agate found on the Priday Ranch near Madras, Oregon, usually in round thunder eggs. This source is now nearly exhausted. Pictures of beautiful Priday plume agate stones can still be found online.

The Regency Rose variety of plume agate is found near the Graveyard Point area. It features the tan hues of Graveyard Point agate, along with reds and pinks.

Regency Rose Plume Agate wire-wrapped necklace by Judi Hogan.

Gem Profile- Moss Agate and Plume Agate

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