Monday, June 6, 2016

Mineral Monday: Close-Ups of Bullfrog Ore from the Original Bullfrog Mine, Nevada

I collected this hand sample from the Original Bullfrog mine, Nye County, Nevada, sometime back in the mid to late 1980s when doing recon in the area, then cut and polished it—probably with a company saw and grinding wheel. This specimen is no doubt the best one I still have (a few may have been lost during one or two house moves), although it's been a while since I looked through all my rock boxes. This one photo has already been featured in two earlier posts, here and here.

I've got a few more photos to show you. These zoom in so we can see the size of the shiny ore minerals contained within the rock: v.g. (visible gold) and a silvery-gray silver mineral.
Here's the other side of this same rock.

We'll be focusing in on the lower left.
I've zoomed in here. Can you see the shiny flecks?
Well, it's hard to see them without holding the rock up to the light and waving it back and forth to get the metallic glint, so I've circled the little bits in yellow and light blue (cyan). Yellow is for gold; cyan is for silver.
See them now?
Yes, these are very tiny flecks of native gold and a silver mineral. The silver mineral is probably either acanthite; Ag-bearing tetrahedrite, with Ag substituting for Cu in the solid-solution series with freibergite; or uytenbogaardtite.
Zooming in even farther, we can see the ore minerals without enlarging the photo.
A few of these show up really well.
Next time I get my hands on this sample—I think it's still up in Alaska—I'll see if I can get even better photos.


John Spoden said...

I spent alot of time along the 8a since 1975 too, Gilman Springs mostly. I remember your helicopter flying around back then. I still camp in Kingston every year and enjoy baths at spencer hotsprings. This year I want to explore the areas behind Taquima caves a little more. I'm more of a amature archeologist although wandering thru the Big smokey I've found spyder silver, lots of cool looking rocks, and other stuff. The big Smokey has lots of cool stuff in the flats if you like walking long distances and stumbling upon points in America hands down, as well as the home of the best point makers anywhere. I used to venture into monitor valley alot when I was younger but stopped doing that because its scary when you get far out all alone. I walked from austin to Kingston Canyon across the Toyabes in the late 70's by myself, would'nt do it today, to many cats. I enjoyed reading about the ole 8A, excuse my spelling, John.

Silver Fox said...

John, thanks for reading, and glad you enjoyed it. I've got a lot of 8A and Big Smoky posts, including the 8A page at the top of the blog. I had to walk part way out of the Toquima's once during our helicopter camp -- you might have already read the little I posted about that! There was at least one cat in the area when we were working there.

I also did feel a little spooked driving through Monitor Valley that last time (see The Geographic Center, and related posts about Monitor Valley). I carry a SPOT when out there; that makes the entire undertaking a little safer. A field partner is also a good thing!

Anonymous said...

You guys are making me nostalgic for Nevada again....Ah..Spencer Hot Springs, I had forgot about that spot.

Silver Fox said...

Spencer search on LFD