Wednesday, July 19, 2017


Let's face it, any long drive is better if you can stop for a bit and find interesting rocks. Recently, my husband and I were on our way to a lovely winery-saturated weekend in Northern California.

Now, winemaking is his thing and rocks are mine. So we decided to make both of us happy! Because we had tremendous rains last winter, a lot of fresh material has washed down to the shallower areas--a great place to check out the rocks.

I'd gotten in touch with the Contra Costa Gem & Mineral Society field trip guy, Chuck who seems to know where all the good pickings are. He recommended a place along Saint Helena Creek in Middletown, CA and we scheduled a stop there. It was right behind the parking lot of Perry's Deli (which makes delicious sandwiches and don't miss the potato salad!) and over some large rocks placed to keep you from driving into the creek.

It was 100 degrees outside when we got there for lunch. I don't do heat well, but there was a nice breeze on the water--and I was motivated.

I spent about an hour checking out rocks along the edge and just inside the shallows. I found one nice small chunk of red jasper. I'd heard that others had found it there and I was hoping to find more, but no luck. I found a variety of rocks, including some that looked like they may have dendrites, which I LOVE to work with. There were a few smaller stones that wanted me to take them home and see about tumbling them, so I did. Finally, I picked up a large, dark, smooth stone. It had dried yellow algae on the outside. I don't often choose dark stones, but this one had some small turquoise-colored inclusions and a nice heft that made me think it might be hard enough to take a shine.


When I got home, I took the picture of the rocks I'd collected, then started trying to discover what I'd found.

I hoped the chunk of red jasper (center left in the picture above) with white streaks would make a couple of eye-catching cabs, so I sliced it . . .  and discovered it was not as cohesive as I'd hoped. Okay, it wasn't cohesive at all; it shattered into pieces too small to use. Into the trash.

The pinkish piece (top right) was a bit light, but it was pink. So I sawed off the end and found I could easily break the end-cap with my hands. Not strong enough to work. Not pretty enough for a specimen. Into the trash.

I cut one rock that looked like it might have dendrites. It was both softer than I thought and muddy enough to make my cooling oil for my saw brown. Into the trash.

I worked a bit of each of the 'tumbling' rocks on the grinder. Mud. Into the trash.


Then, I tried a rock that wasn't terribly exciting, but it wasn't mud. When I tried a corner on my grinder, it polished up a bit. It also had a nice combination of earth tones. Although it wasn't good enough for me to make as a cabochon, it works as a neutral background for wire wrapping.

I cut the next to the largest rock thinking it might be as interesting. Well, it was a conglomerate, but it had the colors and appearance of gray meat loaf that went bad last week. Into the trash.

Test Piece to check for hardness

Finally, I got to the biggest rock and yippee! It's hard, about 6 on the Mohs scale. It's still dark, but has those interesting turquoise colored bits. It polished like a dream. I was suspecting jade, and I wanted some back up opinion so I took a slice and a cab to my rock club meeting. We have a lot of experienced rockhounds and they pretty much unanimously declared it jade. I'm happy with that! Here's a picture of the side of a slice I ground where you can see the green inclusions. What do you think?
Jade rock face with finished cab. Great Shine!   

All in all, with the possible exception of the jade, I didn't find much useful, but I had a lot of fun rockhounding and checking the material I found out to see what it was. Would I do it again? Of course! I'd just try to do it  on a cooler day, so I could hunt longer.

What finds have you found at creeks and riverbeds?

Check back on August 2, for my next blog. Until then, I'm you're Lapidary Whisperer,


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