Be the first to see inside a geode that is millions of years old!
Hand-pick your very own geode from our collection of geodes from around the world. We’ll slice your choice in half while you wait. You never know what you'll find when this volcanic gas bubble, millions of years old, is opened for the very first time.
Our staff LOVE to talk about geodes and will help personalize your experience. Please ask anything you’d like to know!
Click on the video to the left to play
To find out the answers, click on the plus sign 
or the question!
What IS a geode?
A geode is an unusual, rounded mineral formation typically with an exterior shell of chalcedony (very fine-grained quartz), with other minerals and / or crystals lining the interior. The name geode is from the Greek geo referring to the shape of the earth, since most geodes are spherical.
A geode can form in any cavity within a rock, but the most common method for geode formation is via gas bubbles that form in cooling ash beds. The bubble gets “frozen” in place when the silica rich ash / dust hardens. The partial or complete filling of the bubble may occur immediately or even thousands to millions of years later and can encompass a variety of different minerals.
Geodes can also be filled with surrounding silt and sediments, forming a “mud ball.” If a crystal breaks off inside the geode, you can hear rattling (the only guarantee of a hollow geode!), hence the nickname “rattlestone”. Occasionally, water gets trapped in the geodes, forming what is called an enhydro, Greek for “water inside”.
Geodes are fascinating and unique forms of nature, and like fingerprints, no two are exactly alike!
How much is a geode?
Geodes start at $8.99 and go up to over $200. The price is determined by the size of the geode and there are a variety of sizes and prices to choose from.
Does the price include cutting?
Do I get to keep both halves?
Yes! When you select a geode, you keep the whole thing. We are however, very happy to accept donations for our geode display.
What if there’s nothing inside?
We have nicknamed geodes “Mother Nature’s Lottery Ticket”, because you never know what you’re going to get until after it’s been opened. But since you’re starting with the remnants of the “bubble shell”, you’ll always have something to bring home as a souvenir of your visit to The Dinosaur Place™!
Can you tell me what color is inside?
Unfortunately, we do not have any way of determining what the inside of a geode looks like. We can however, tell you which mine a particular geode is from and show you similar geodes. Keep in mind; every geode is one-of-a-kind, and beautiful in its own way.
6 to 8 million years ago, volcanic activity in Western Utah deposited an igneous rock called rhyolite. Trapped gases formed pockets in the rhyolite, which eventually became lined with chalcedony and quartz from groundwater. Most Dugways fluoresce a lime green color due to minute amounts of a secondary mineral that bonded with the quartz when it was growing. 32,000 to 14,000 years ago, a large lake covered most of Western Utah. The lakes wave activity eroded the rhyolite and actually moved the geodes several miles away to their current location in Juab County, Utah. 
Choyas geodes are mined in a 44 million year old volcanic deposit in an area of Chihuahua, Mexico called Las Choyas. Nicknamed “coconut geodes” because of their roundness and size, Choyas are literally hand dug with a pickaxe out of a tough bentonite clay. Miners fill potato sacks with the geodes and raise them up narrow shafts from 75 to 125 feet beneath the surface! Composed mainly of any variety of quartz, including the ever-popular amethyst, Choyas are especially fascinating because of the wide variety.
Septarian geodes formed 100 million years ago when the Gulf of Mexico reached up to southern Utah. When sea life died, it became trapped in sediments and formed mud balls. As the sea receded, the mud balls dried and cracked in the sun. The sea returned, and calcium from newly decomposing shells eventually seeped into the cracks and re-crystallized as calcite (yellow.) The thin brown wall is aragonite and the gray exterior is bentonite clay. The name Septarium comes from the Latin “septum”, meaning dividing wall.
Brazilian geodes are found in a large open pit mining operation in Rio Grande de Sol, Brazil. These geodes are filled with beautiful layers of banded agate that form under relatively low temperatures of 45-54°F and pressures. A striking feature of the agate is the occurrence of dendritic inclusions resembling trees, bushes or even sunbursts, caused by a mineral growth of manganese oxide.
Thunder Egg geodes formed in volcanic ash tuffs in the Pacific Northwest 20 million years ago. These remarkable geodes have a beautiful star shaped pattern of chalcedony with colored agate filling the middle. The name Thunder Egg originates from an old Indian legend that states two angry gods located on neighboring mountains got into a violent fight and used eggs taken from the nest of thunderbirds as weapons. After the fight, the “weapons” were found scattered on the ground.
Potato geodes, mind in Chihuahua, Mexico, are sometimes called Mexican Thunder Eggs because of their similarity to the Thunder Eggs of the Pacific Northwest. Geologically, they are considered lithophysae (lithophysae is Greek for “rock bubbles”). The geode shell is a volcanic rock called perlite. When perlite is formed with a high water and silica content, quartz crystallizes out of the perlite in a radical form and discharges water as hot vapor, forming a cavity. The hot vapor in the cavity grows outward and expands into a star-shaped hollow.
Miners named these unusual geodes for their incredible resemblance in color and shape to sweet potatoes. As a very recent find, little information is available on these geodes. The exterior shell is believed to be red jasper and the interior is typically filled with layers of blue or white chalcedony.
These fragile, thin-walled geodes are mined in the town of El Dama in Chihuahua, Mexico. The name Trancas comes from an abandoned railroad station, “El Staciòn Trancas” located near the mine. Trancas formed 11 million years ago under unusually warm conditions. They often contain stalactitic quartz (delicate quartz projections) rather than traditional hexagonal crystal quartz. Trancas commonly fluoresce due to trace amounts of a secondary mineral that bonded with the quartz while it was forming.
Join Us
on FaceBook!
