Crushed and panned out some of that grey colored volcanic rock I collected two days ago. Appears to be plain old basalt. Before doing anything with it, I ran my Falcon over the material, just to see if I could get lucky. I didn’t although several pieces were metallic, although ferrous. Hard to tell what they are and iron related pieces are common seemingly everywhere a prospector goes.
I crushed and panned out some rocks to fifty mesh, producing a few gold glinting specks in the pan. Always assume pyrite or mica. I had found mica on the hill on my last trip but pyrite I suppose was possible. One fleck did interest me because it appeared corrugated and granular, not flat like mica.
The piece turned out to be mica, though. Didn’t need the scope. Looking at the piece on its side with a 10X loupe showed its platy character, that onion skin like texture that mica has, in the way it can be peeled back in sheets. I rendered the image below into monochrome.
By Pascal Terjan from London, United Kingdom – MicaUploaded by Magnus Manske, CC BY-SA 2.0, Link
I’m a total beginner with a microscope. I use this plastic lid with embossed lettering to orient me. I place a speck of something near some letter and I can then find the speck near the letter. Everything is reversed under my scope. Move something to the right and it goes to the left.
Chief problem with any microscope work is keeping stray animals from interfering. John Charles Fremont The Explorer was tremendously interested in my project and repeatedly tried to help. Alas, no help at all. I usually hook up the scope to my desktop computer since the microscope camera draws power from a USB port. I have not yet heard, however, my laptop’s fans come on. So, the draw must be low. My LED lights are powered by the mains, I wish they were dimmable.
Another view of my setup. Note the lettering of the lid on the computer screen that I mentioned before. This is a Chinese scope that I could afford. Not the best optics but an integrated digital camera. Without such an approach, you are forced to kludge together a scope with a digital camera that you might have, trying to get various lens adapters to work, finding the right lens to begin with, and so on. Nightmare.
Crushing out the bigger rocks on an empty road with my hand sledge and a small rock crusher.
Crushed pieces revealed a fair amount of quartz. That surprised me since none was visible before I broke the rocks down. But quartz is one of the biggest rock building minerals so perhaps this is not surprising. Perhaps this is not even basalt, rather something more granitic.
I will try to get back to the Pass tomorrow to get some samples from the gullies I mentioned in the last post I wrote at my personal writing site. Click here to go there.
The Alunnite Mine, Alunite Mining District, Clark County, Nevada, USA (Link to Mindat.org)
Clark County image from the:
Index of Granitic Rock Masses in the State of Nevada By FLORIAN MALDONADO, RICHARD W. SPENGLER, W.F. HANNA, and G.L. DIXON
Prepared in cooperation with the U.S. Department of Energy
A compilation of data on 205 areas of exposed granitic rock masses in Nevada
U.S. GEOLOGICAL SURVEY BULLETIN 1831
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Rupprecht Estate Rock
Care of Jason Fabbi G.G.
East Las Vegas, NV
Small rock yard representing more than sixty years of collecting in the Southwest by Ed Rupprecht and his wife. Mostly rocks that take a cut and polish, little in collectible minerals. Mostly rough, some slabs. Please bring cash in small bills. Rocks in general are two dollars a pound, slabs more, some things different. Ask Jason for particulars.
Bring your UV lamps, there is a barn like structure on this property with good darkness. I got plenty of pretty lime/green pieces in quartz like rocks, no red or unusual colors. It was not a calcite fest, either, which was good. And I only had a SW lamp, so your luck will be better if your portable lamp has all three wavelengths. Pet wood, opalized wood, a septarian nodule or two, rhyolite, and on and on. Well worth looking at if you are in Las Vegas.
Contact Fabbi to see if the yard is open. Jason is an extremely talented jeweler with a long history of collecting and finishing stones. He is very active in the local club, the SNGMS and does much custom work. He made a handsome bolo tie for me out of gold in quartz that I found.
Handheld iPhone photo in SW just to give you an idea. 18 watt Way Too Cool lamp.
Picture of the rock yard.
One more picture.
And a video.
Estate rock yard of the late Ed Rupprecht in East Las Vegas from Thomas Farley on Vimeo.
A great man.
A few days ago I had to leave Las Vegas on an emergency trip to help out some friends. The couple I know owns a hundred acre horse ranch in Amador County, in the Sierra Nevada foothills. Their spread is near Plymouth. The heart of California’s Mother Lode Gold country.
When this husband and wife first bought their property I came out with my gold detector. I was delighted to find broken quartz everywhere. Most displayed iron staining and many contained vugs or cavities.
Alas, only a small speck or two of gold was found in a shallow ditch running through the acreage. The nearby creek had been dredged for gold but my friends didn’t own any of that stream. Nor did they own property containing any tailings.
Never-the-less, the many small pieces present might be useful one day for tumbling, as their dark vein patterns contrast nicely with the quartz matrix or host rock. Even if you can’t find gold, you can often find something else.
Iron staining and vugs are signs of mineralization and activity within a rock. Something has acted on the stone. Most quartz is barren, white colored with no character. Sometimes called bull quartz. You look for character when you look for gold. Decomposition or crumbling quartz is another sign to watch for.
Having said all this, the finest gold in quartz I have found displays no other minerals save a scattering of the gold itself. My specimens are milky to near pure white with only gold showing in the matrix.
The lesson is that if you have the time, detect all quartz, even that which looks sterile. If you don’t have the time, limit your search to quartz that shows mineralization or the effects of forces which have altered the rock.
The quartz on the left shows iron staining, the material on the right shows vugs. These have not been cleaned and both show the clay soil of the area.
The larger rock might make one or two interesting slabs. The smaller pieces might be tumbled.
Agates occur in nearly every state, along with countries around the world. Their patterns are endless and often striking, sometimes unbelievable. Right now there is a great agate thread going on on the open Facebook group Rockhound Connection:
Make sure to check out the posts. They are all variations of quartz.
As beautiful as some of these cut and polished specimens are, many beginners are confused as to what to look for. Although not always present, a certain translucence and a wavy character to the rock are good signs. Some agates are so outrageously striped that there is no doubt as to what they are.
Here is a video of an agate that I liked so much that I have never had the heart to cut it open. The second photograph shows another agate from the same location, one I cut into a slab with a rock saw.
Both of these rocks are for examples only, they did not come from the Southwest. But if you are ever in Northern California, you may want to check the riverbed of Cache Creek in Yolo County. Good luck.
Uncut agate. Click on image or text link below. (Movie)
Just started photographing small specimens. This is a far greater challenge than taking pictures of hand sized rocks and minerals. Although I am not happy with the shot below, it is interesting.
Feldspar and quartz are the two most common minerals on the planet. The photograph shows feldspar with its “blocky crystal habit” and smoky quartz, with its six sided crystal form. Feldspar doesn’t get much love because its color isn’t exciting and because it is so common.
A mineral’s outward crystal expression is the manifestation of its inward atomic structure. If we were to peer inside feldspar at high magnification, we would see that feldspar’s atoms were arranged in the same blocky pattern that is exhibited on the outside. Provided one important thing.
Conditions must be right for crystals to develop into the shape you see here. Under poorer conditions, a lack of room for example, feldspar crystals would not express themselves and this specimen would be just another lump of dun colored rock. Quartz is often associated with feldspar.
More good information here: