Gem Profile- Thundereggs and Mexican Lace Agate

by Judy Ellis

Thundereggs and Mexican Lace Agate, part of our Series on Quartz

Thundereggs

You've probably heard the story told to children during thunderstorms: "Oh, that's just God and the angels bowling. Did he just get a strike?"

Legends from the US Pacific Northwest say that Thunder Spirits lived atop Mount Hood and Mount Jefferson. When angry with each other, they would throw rocks specifically thundereggs.

These mischievous spirits supposedly stole the eggs from the nests of Thunderbirds, mythical powerful birds often depicted on totem poles.

Thundereggs, also called lithophysae or rock bubbles, look like ordinary rocks from the outside, usually the size of a baseball or softball, though some can be taller than a person. When sliced open, they reveal stunning agate formations.

Thunderegg agate from the south of France. (Image property of David Rix Eibonvale)

While similar to a geode ordinary on the outside and beautiful within thundereggs are only true geodes if they have a cavity or hollow inside. Many thundereggs are completely solid, filled with agate.

Although agate is most common, some thundereggs contain jasper, opal, quartz, selenite, or combinations of these stones.

Like other agates, thundereggs form from rhyolitic lava flows, slowly cooling and solidifying inside cavities.

Scientists still debate the exact process, but one common theory suggests molten or cooling rhyolite was ejected from volcanoes as projectiles called volcano bombs.

The molten agate then landed in volcanic ash and slowly formed thundereggs.

In a sense, the Pacific Northwest tribes may have been right these volcanic "dwellers" did throw the rocks!

This thunderegg is from the Black Rock Desert in Nevada.

(Image property of David Rix Eibonvale)

While Oregon, home to Mt. Hood and Mt. Jefferson, is the most famous location for thundereggs, it was officially designated the Oregon state rock in 1965.

Thundereggs can also be found across the US and Canada, as well as in parts of Africa, Madagascar, Central Europe (Poland, Romania, Turkey, France), Australia, Mexico, and Argentina.

Their presence in these regions makes sense, as thundereggs form in historically volcanic areas.

Frances Lediaev wrapped this agate geode slice in silver wire to create a pendant.

Mexican Crazy Lace Agate and Laguna Lace Agate

Mexican Crazy Lace agate typically comes from mines in northern Mexico and has been widely popular in lapidary and jewelry since the 1950s.

Mexican crazy lace agate has also been called Rodeo Agate and Rosetta Lace Agate by various sellers and mine operators.

Crazy Lace Rosetta Stone Cabochon Pendant wire wrapped by Joan Madouse in gold craft wire

Unlike the calm lines of Botswana agate, Crazy Lace agate has erratic, lively banding patterns.

Its bands feature a wide range of colors, including red, yellow, white, gray, and pink, often resembling an Indian paisley design.

Crazy Lace agate can also be dyed vivid purples and blues, sold as Purple Crazy Lace Agate or Blue Crazy Lace Agate.

Mexican Crazy Lace agate is found in Cretaceous-age limestone, making it 65-90 million years old.

A Crazy Lace rosetta stone cabochon wrapped in bronze wire by Joan Madouse.

Laguna Lace agate is a specific type of Mexican Crazy Lace agate.

Other variations include Bubble Lace, Cactus Lace, Chinese Writing Lace, Dog Tooth Lace, Fine Line Lace, Victors Lace, and Zebra Lace names that often hint at their patterns.

Some are named for the town or area where they were found.

"Laguna Lace Agate" describes a variety that resembles a cross between Mexican Crazy Lace agate and Laguna agate.

Laguna agate, also from northern Mexico, is a highly sought-after banded agate known for its stunning beauty.

Joan Madouse wire wrapped this Mexican Crazy Lace agate in a rectangular frame with matching swirls of silver craft wire.

Laguna Lace agate is found in Chihuahua, Mexico, near the original Laguna agate discovery.

The desert agate deposits start about 83 miles south of El Paso, Texas.

Chihuahua, Mexico's largest state, experienced an "agate rush" for roughly 50 years until the late 1960s.

While it lacks the clear, highly valuable banding of Laguna Agate, Laguna Lace agate still displays fortification banding.

When first sliced, the bands resemble a bird's-eye view of a medieval castle fortress wall.

This agate is commonly found in blue, but also occurs in a rainbow of colors: orange, white, cream, yellow, black, gray, pink, red, and green.

Linda Pope wire wrapped this blue Crazy Lace agate cabochon with copper wire and added Swarovski crystals and goldstone chip beads as accents.

Resources

The Formation of Thundereggs by Robert Colburn, aka "Paul, the Geode Kid" at https://www.zianet.com/geodekid/thndregg.htm
Thunderegg on Wikipedia.org
Thunderbird on Wikipedia.org

Gem Profile- Thundereggs and Mexican Lace Agate

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