Went back today to the area where I found a field opal that displayed beautiful conchoidal fracture. Weak response under UV, perhaps I could find something better. Or perhaps something else, because you never know what you’ll find when you start walking around.
— Never a fashionista, I set out into the desert wind with a light rain jacket. Fleece is great until heavy wind comes up, especially when you arrive at a summit. Impervious material beats loose weave fabric any day. I have splotched sunscreen all over my cheeks as I had some skin cancer taken off my face last year. A dermatologist said it was “a small price to pay for being outdoors.”
Click on the “View Larger Map” selection in the upper left hand corner to call up the map.
Here’s a simple geologic map from Macrostrat.org, Alluvium mostly, present in every Nevada county, along with the Nopah Formation and the Banded Member Formation. Limestone mostly, marine rocks, a lot of sediment. Nothing metallic indicated. I think, generally, most rockhounds favor finding igneous rocks, volcanic related materials, harder stuff. But I look for everything.
On this trip I was especially watching for ripple marks which are ancient wave movements captured in hardened sediment. These are sometimes found in desert washes, in fact, I had a field trip member find one on a trip I was on in the Calico Hills outside of Barstow. I was happy having found a nice piece of sandstone with dendrite markings. Until then. I am still jealous.
I was recording snippets of video and at one point I let the camera run. A rule is to always inspect gaudily colored rocks. Or those rocks that stand out whenever everything else looks the same. —
Here’s a closer look at the orange coated or colored rock, the back of it exhibiting cracked limestone, what’s called a solution surface. This is not lichen, I know that. I’m a plant guy. This material goes well into the rock, revealed when I broke off a piece. To find out what it is, I’ll take a closer look at the area’s geology and I will send off a sample to Kerry Day in Canada, who does mineral testing for only eight dollars a sample. He’s a good guy:
And a video of the rock, showing it a little closer.
36°34.09833′ N 116°04.43667′ W 36.568306, -116.073944
I took a half bucket of interesting rocks home and only a handful showed any promise. Many fluoresced but only slightly so. Most had calcite touches which is everywhere in the desert. I do have a large lid that looks like a bar-b-cue cover. I could have tested these rocks at the tailgate with my portable SW lamp but I didn’t bring either along. In fact, I really started the day intent on gold prospecting. Another time.
None of the material registered on my hand held metal detector or my geiger counter. I was sad but not surprised, there was nothing in the area’s geology to support either one.
Here’s what glowed well when I got back home, the orange rock showing afterglow or phosphorescence. Just a tiny bit, but as you can see by the video, the light was so low that the iPhone couldn’t catch it. I went back later to see how my Nikon would shoot video. I apologize for saying “surface coating” in the video. Limestone showing a solution surface is a thing, you see it everywhere in marine hills.
The Nikon was a bust. It should have done better in low light with its full frame sensor but it did not. Here instead is a slow motion of the afterglow. This much better represents what I see in person. Really good rocks that collectors want will glow for ten seconds or more. This rock is just nice for me, something I found and now a place I can visit again to perhaps find more.
For reference, here is what real afterglow looks like. These are rocks from the Scott Mine in Arizona. Willemite is green, calcite red. This was a generous gift from Cliff Jackson. This is real time video, no need for slow motion. Again, though, looks much better and goes longer viewed in person.