When I was a kid, back in the 1960s, my mother and dad took up a hobby of lapidary. Bonnie Gay was always hunting for special rocks and Indian artifacts. When it came to arrowheads and such she had a real knack for it. She had a very collection.

She was walking down the old road from our house to the lake one day. When I say the old road, we had quit using it and another route had been taken for the road, which had a lot less of a grade. It is still being used now all the years later. It was the stretch of road just above the old Lewis Homestead House where all of my grandfather, Theron and his siblings were raised.

The abandoned road was just too steep and rocky. Bonnie Gay was walking down the old road and looked down and found a rock that looked identical to a walnut, in size and color. There was a pattern on it that made it look like a walnut.

Cecil had just bought a small tabletop saw with a diamond wheel for cutting a shaping stones. He even made a tumbler – polisher. They were spending a lot of time out on the front porch of our house down on Bull Creek, out of Jollyville working on all sorts of creations. I don’t think they had a means to sell anything, but they were giving them out as gifts to family and friends.

Cec was always curious about things so he had to cut into that walnut shaped rock. He was holding onto one side of it and when it sawed all the way through, the inertia from that saw blade threw the other half out into the yard. When I say yard, there was nothing there that resembled a yard. There wasn’t a blade of grass or any other vegetation. We ran goats on that place and they had everything pretty well eating down, leaving nothing but a rock pile for a lawn.

We looked and looked for the missing half but never for it. But when he started polishing that thing it was the most beautiful blue color on the inside. We were just sick that we couldn’t find the missing half.

Well when we got back up to Smithwick, Bonnie Gay went back to that old roadbed to see if she could find another. She was tickled to death when she came up with another “walnut”. She continued to scour that hillside for the rest of her life but never found a third one.

When Cec carefully cut this one, it was the most beautiful red color when it was polished.

Those prized stones stayed with her collection. I don’t remember her ever mounting them. I always thought they would have made a great bolo-tie or brooch. It think she didn’t want to let them get away. After she passed on, her collection rocks and artifacts went a thousand directions.

I started wondering the other day what those walnut looking rocks may have been. Following is the closest thing I could come with. Thundereggs.

One wouldn’t think that they would have made their way to Smithwick, Texas.

Per AI:

The stone you’re describing is likely a geode, specifically a type like an agate or quartz geode. From the outside, many geodes resemble a walnut due to their rough, rounded, and sometimes bumpy exterior. When cut open, they can reveal vibrant colors inside, including red or blue, depending on the minerals present. For example:

• Red interiors can result from iron oxides or other mineral impurities.

• Blue interiors are often seen in agates or chalcedony, where trace minerals like copper or cobalt create blue hues.

Geodes form in volcanic or sedimentary rocks, with cavities filled by mineral-rich water that deposits crystals over time. The “walnut-like” outer shell is typically a tough, unremarkable rind, while the inside can be a stunning surprise of color and crystal structure.

A thunderegg is a type of geological formation, typically a nodule-like rock, similar to a geode, that is often spherical or egg-shaped with a rough, bumpy exterior resembling a walnut. It is formed in volcanic ash beds or rhyolite lava flows, where silica-rich water fills cavities and creates a hard outer shell. When cut open, thundereggs reveal a variety of internal structures, often with colorful patterns or crystal formations, which can include shades of red, blue, or other colors due to mineral inclusions like agate, jasper, or opal.

• Exterior: The outer shell is usually drab, knobby, and tough, often compared to a walnut or potato.

• Interior: When sliced, thundereggs may display intricate patterns, such as star-like or mossy agate, or vibrant colors (red from iron oxides, blue from silica or other minerals).

• Formation: They form when gas pockets in volcanic rock are filled with mineral-rich fluids, which solidify into chalcedony, agate, or quartz over millions of years.

• Locations: Thundereggs are found in places like Oregon (the state rock of Oregon), New Mexico, Australia, and Germany.

Unlike true geodes, which often have a hollow cavity lined with crystals, thundereggs are typically solid or have partially filled interiors with agate or jasper. Their name comes from Native American folklore, which associated them with “thunder spirits” due to their discovery in volcanic areas.

If you were referring to the stone in your previous question that looks like a walnut and can be red or blue inside, a thunderegg fits this description well due to its walnut-like exterior and potential for colorful interiors.