GIANT thundereggs at Priday Polka-Dot Agate Beds: LAPC

North of Madras, Oregon, you’ll find giant thundereggs tucked away on a hilltop near the ghost town of Ashwood. Polka-dot agates and thundereggs occur naturally at the Priday Polka-Dot Agate Beds.

Agate beds

The thundereggs you’ll find here are amazing! You never know what kind of treasures you’ll find on the inside.

Close up of rock

Giant thundereggs

I was impressed by the layered, colorful rock formations alongside the road on the drive to the site.

Rimrock drive

Near Priday polka-dot beds

When we arrived, we were told where to dig and what to look for. The staff were friendly and knowledgeable about the local geology. Samples of rough, and cut and polished rocks were on display.

We asked if it was okay to bring our dogs while digging. They said we could and admitted to liking dogs more than some people. 😉

Giant thundereggs galore!

We brought our own rock hammers and bags, but they provide them for free. I noticed they had five-gallon buckets for collecting rocks and soon learned why. There are HUGE thundereggs here! I put a ruler into the picture below to show the scale of rocks we collected.

Giant thundereggs

Some of the thundereggs at the Priday Polka-Dot site have mini stalactite or stalagmite-type formations inside. Collectors are fond of this type of thunderegg.

Inside thunderegg

We both worked on prying thundereggs free from the substrate. It’s not easy work, but recent rainfall loosened the soil.

I always look at the rocks other visitors cast aside. You can find real treasures in these piles!

Rocks near digging area

We had a couple of our finds cut in half. There’s a small charge for this service, but it’s worth it.

Rock cutting station

Just a reminder… rocks are HEAVY! They charge $2.00/pound for the thundereggs. I like rocks a lot so I thought it was worth the price.

Thunderegg cut in half

We’ve collected thundereggs at Richardson’s Rock Ranch, south of here, several times, but the thundereggs at the Polka-Dot site are much bigger. Richardson’s no longer allows public digging, but it’s a good place to get extra-large thundereggs cut. They also have an excellent rock shop, including rocks with origins from all over the world for purchase.

Other rocks for sale

You’ll see large piles of various types of rocks for sale near the parking area at the Polka-Dot mine.

Rocks for sale

Rocks for sale

Polka-Dot Agate

The polka-dot agate mine near the thunderegg site was not open for digging during our April 2022 visit. There’s a huge boulder of polka-dot agate near the cutting area and small samples nearby you can buy.

Polka dot agate

I bought a small piece to bring home. Black, brown, and red polka-dots are scattered across a white or light blue base on these agates.

Polka dot agate

Fire Opals

The Priday Polka-Dot Agate Mine also has fire opal for sale but I misread the sign as $2.00/pound when it’s actually $200/pound. Ooops! Here’s a small faceted piece from a mine in southern Oregon that I purchased a while back on eBay. The Juniper Ridge fire opal mines are privately owned and there’s not currently a dig site open to the public.

Fire opal


Check the West Coast Mining website for operating hours or call ahead to make sure they’re open.

To get to the mine, drive 15 miles north of Madras on Highway 97. Look for the sign to Ashwood and head east nine miles on a winding, scenic road.

You’ll know you’re at the right spot when you see the polka dot-painted trailer.

Priday Polka Dot Agate Bed

An added bonus

When we were there in late April, we were happy to see one our local wildflowers in bloom. The magenta blossoms of the snowball cactus were beautiful!

Snowball cactus

Snowball cactus

We will visit the Priday Polka-Dot Agate Beds again in the future. It’s a wonderful site to find incredible giant thundereggs – and our dogs had fun too. 😀

Lens-Artists Photo Challenge – Treasures

16 thoughts on “GIANT thundereggs at Priday Polka-Dot Agate Beds: LAPC

  1. Siobhan, what a wonderful, informative post! I have read of something new to me! I am fascinated by rocks and have been collecting rocks and stones since my childhood! Thank you so much for sharing your treasures on this challenge!

    • Yes, they do! They are the state rock here in Oregon. Yeah, I was impressed the owners went to the trouble of creating a sign to protect the cactus plants. 🌵

  2. I’ve never heard of thundereggs – they look fascinating and beautiful! I’m really surprised people are allowed to take them away. I would have expected it to be a ‘leave nothing but footprints, take nothing but photos’ site.

    • Yes, this is one of the mines where people pay to take home their treasures. Our state rock is popular with visitors because you never know what surprises lie inside. 🙂

  3. LOL for your misreading the price sign Siobhan, I’m thinking maybe you passed on those but your small opal is really beautiful. I always thought they were only those milky blue colors. Really interesting post, was totally unaware of these.

    • Yes, Tina, it was funny. There was a hole after the 2, so it looked like decimal point. The fire opals don’t look like precious opals at all. Both have their own version of “fire.” 🙂

  4. Great treasures Siobhan! They really look like eggs and I can understand why you think they are worth $2 per pound. I’m wondering what they would look like polished. Maybe you’ll show us someday.

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