Friday, October 1, 2010

Liz and the Limb Cast

I had never heard the term limb cast until the day before I found one. It all started when my husband, Derrill, and I sent for a DVD course on geology. Shortly after that, he bought a rock saw and began cutting rocks in two. After that, he got a polisher, and soon we decided we'd try rockhounding when we took our fall ramble to see our son in Nevada.

We loaded the 2quads on the pickup, hitched the trailer on behind, and headed out.

Nevada is a rockhounds' mecca, and we were wildly successful when we went looking for wonderstone and jasper around Fallon.

On our way back to Washington, we decided to stop in Central Oregon and spend a day there. But what to look for? That's when I read about limb casts in the guide book.

A limb cast is a particular type of agate. Agates are formed in volcanic voids. Water percolates into the void and silica dissolved in the water crystalizes into agate. Other trace minerals give agates their color. With limb casts, the void is created by a tree being covered with hot volcanic ash. The tree limb burns away, but the volcanic material around it forms a mold of what the limb used to look like. Agate forms inside the cavity, and aeons later, some rockhound finds the treasure.

So, flush with our success at the wonderstone site, we decided to go look for limb casts. The guidebook used discouraging words at some sites--it's been picked over, you might only find chips, etc.--but not at the site around Palina. That's where we headed.

I might mention that the time we picked to go to Nevada and Oregon, they were having record Indian summer temperatures. Derrill and I both are athritic, so walking for a long ways isn't an option. Add to the fact that we're used to walking at sea level and this is 4500 feet.

What I'm trying to say is that searching for limb casts on the hillsides around a ravine was tough, hot, going. I was carrying a rock pick and a spray bottle of water to wash off stones with, but mostly I used the spray bottle on myself to cool me off.

I found some small chips and a larger piece about 4" by 1/2". Derrill used a pick and shovel to mine the bank of the ravine and found nothing. By mid afternoon, we finally decided to pack it in and head back to town where the guidebook said we could see an agatized pinecone that was beautiful.

We loaded the quads and headed back on the very primitive road. Derrill stopped to check the tiedowns, and I looked down at the ground by the side of the road and saw something shiny peeking out of the dirt. Thinking it might be another chip, I got out and picked it up. Lo and behold, it was a limb cast. It was pink agate and weighed about 2 pounds.

As soon as we got back to the RV park I went on line to look up limb casts. I found out that pink limb casts are highly prized. Well, I'll tell you, I highly prize this one. Never mind that I found it while sitting comfortably in an air conditioned pickup. I had sweated and panted, stumbled and creaked for the five hours previous, and I smile every time I look at it.

I didn't take a picture of it, but you can see the marks of the bark on the outside of the pink agate.
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Tina Scott, the writing artist said...

I took a geology class in college and loved it. I've never heard of a limb cast though. Pretty incredible.

Liz Adair said...

I think it's incredible, too, Tina. I put it through the dishwasher to get it cleaned up, and now I have it on a shelf with some other rocks. I smile every time I look at it, thinking of my luck.

GoofyJ said...

Very incredible! This post took me back to my childhood when my dad would stop at random places along the road to hunt for rocks. We would go home from any truck with a van laden with rocks.

Deirdra Eden-Coppel said...

I love your site and as I browsed your blog I decided to award you the Powerful Woman Writer Award.
Go to and pick up your award.

Liz Adair said...

Well, thanks Deirdra. I didn't feel very powerful after stumbling around that ravine, but I'll accept it anyway.