Geodes come in all different varieties but the most popular variety is the ones lined with crystals which make them very popular for rock and mineral collectors. They can be found on every continent and range in value.
Some of the most common types of geodes include the following:
- Amethyst geodes
- Potato stones
- Calcite geodes
- Quartz geodes
- Volcanic geodes
- Sedimentary geodes
The three ways geodes form are water erosion, sedimentation, and volcanic activity. For example, geodes such as thundereggs form when silica is trapped in magma pockets. These form a stunning, glass-like interior speckled by crystals.
Others, such as potato stones, form when water pools underground. As the water settles, minerals collect along the cavern’s walls and form crystals. Eventually, the pool of water dries up, leaving behind a hollow cavern with tiny crystals.
Other varieties are named for the dominant crystal found inside, such as amethyst geode or calcite.
Geodes are an impressive geological formation. Although not a rare occurrence, all geodes take special conditions to form correctly.
This process includes the following conditions:
- Air pockets form in magma
- Caused by tree roots, animal burrows, or large pockets of gas
- Moisture and mineral deposits collect along the wall
- Endure extreme heat and pressure
- Over time, crystals form along the walls of the cavity
Which Geodes Are the Most Valuable?
The most valuable geodes have high-quality deposits of crystals and are quite large in size.
However, small crystal geodes have a market as well. These geodes, which include potato stones, are popular gifts for kids. While you won’t make hundreds of dollars per geode, you’ll have a loyal clientele!
Most geodes are sold by the kilo. This means if you find a geode with a thick outer casing, you’re probably paying more than you should.
White geodes are worth
A white geode has milky quartz crystals or calcite crystals lining the inner walls of the geode. These are not as rare as amethyst geodes which means their not worth as much per kilo. This doesn’t mean they’re not cool to look at or lack uniqueness. Just make sure you don’t overpay for them.
I would make sure that I didn’t overpay if I was looking to add these to my rock and mineral collection. If I was going to purchase a white geode then I’d be willing to pay between $2 and $25 per kilo.
Purple geodes are worth
Purple geodes are geodes lined with amethyst crystals and tend to be more rare than white geodes. The value of an amethyst geode is driven by the quality of the amethyst and the overall size of the geode. The dark purple amethyst will sell for quite a bit more than the lighter-colored amethyst. The best way to value or price an amethyst geode is to walk the Tucson Gem and Mineral show to see what dealers are asking. This gives you the most up-to-date pricing. If you’re unable to make the trip to Tucson then I’d fall back on eBay and online listings.
I’ve found that Amethyst geodes are priced between $8 and $125 depending on quality, size, and uniqueness.
The most valuable geodes have dark purple amethyst and black calcite. This is due to a combination of beauty and rarity. Amethysts and black calcite are relatively rare compared to limestone and clear quartz.
Quartz geodes are worth
Geodes with druzy quartz crystals are the most popular because you can buy them anywhere. The smaller ones are great for junior rockhounds and can be purchased for $5-$10. As you move up in size you should expect to pay more. I’ve found the best druzy quartz geodes come from South America and you can buy them online or at a local gem and mineral show. You can expect to pay between $25 – $75 for a geode 8 inches in diameter.
These make for great gifts, especially if they’re polished along the rim and the druzy quartz is crystal clear.
What Are the Best Ways to Buy and Sell Geodes?
Buying geodes in bulk from a dealer at the Tucson Gem and Mineral Show is the best way to acquire geodes at a discount. You’ll need to have a diamond saw to cut them open and a flat lap for polishing the edges. This ensures you’ll get the most for each geode.
- Select a spot to dig (The American midwest, Mexico, and Uruguay are the best spots to search)
- Check with the local state or national geological surveys
- Join a rock and mineral club in your state
eBay or Etsy are excellent places to start selling your crystals!