— These are calcite display pieces that I cut from rock I gathered at that ancient and now dry hot spring near Shoshone, California.
I showed photos and videos of this site on Instagram.
Someone had dug a large pit into a barren hillside, digging out I know not what. But I gathered some of the spoils on the downside of the digging. The rock revealed calcite as it typically forms around hot springs. Similar in some ways to Kokoweef Cavern calcite.
It’s the hot spring you can take with you!
I have one polished piece. It doesn’t look as nice as the unpolished pieces. There is also one rock of rough, waiting for you to cut up.
No plans to sell online because postage is so outrageous. You’d spend half your money on mailing. Sigh.
Best in the West is in Pahrump on the corner of Winery Road and Homestead. Look at the top menu bar for more information.
— I stumbled upon this old navigation aid for pilots near Jean. After some research on the web, I found arrows like this are scattered across the country. They were used along with beacons to help pioneer mail delivery by air in the 1920s and 1930s. The website below is fascinating. Lists arrows in every state along with many details. Tons of photos of arrows and their history. Do you have one in your backyard?
“These giant arrows were called Beacon Stations and helped guide the pilots of early airmail flights across the nation. They were at the base of 50 foot skeleton towers that had a 24″ or 36″ rotating beacon and in the early days painted Chrome Yellow. Where electicity was unavailable they had a generator shed on the feather end of the arrow to power the beacon. The site number was painted on one side of the roof of the shed, the other side had the airway.They pointed to the next higher numbered beacon station, directing the pilot along his route. All arrows pointed east on the west-east airways and north on the south-north airways. They were built between December 1926 and November 1932, when metal arrows became the standard.” —
— Quick handheld iPhone photography, apologies. Rock found in desert wash. On the left, the rock glows orange (calcite), green (quartz) and a little bit of white from an unknown mineral coating. This under short wave. On the right, the green and white disappear completely under long wave while the orange stays strong. — Follow me on Instagram: tgfarley
Important note from RC. The limestone comes first, not the calcite. In the post I have the process reversed.
Saturday, September 14, 2019
Picked up an odd rock today along the Old Spanish Trail, not far from the Junction of Highway 160. in Clark County, Nevada. What Macrostrat.org calls young fan alluvium. Lots of limestone and sandstone bits and pieces. Didn’t see anything like this rock. It has notable pockets around the rock and then lines of heavily marked material evenly radiating out from them.
There is chunk of what may be limestone at the bottom of each pocket. It reacts little to acid but I think I see some activity. The white material, less that 2 on the Mohs scale doesn’t react because it is so porous the acid soaks it up before doing anything! The white material fluoresces a strong orange/red while the pockmarked lines, full of circle and bubble shapes, does not do anything under UV.
It strikes me somewhat as being like the calcite material which I saw recently at the Kokoweef Cavern Mine complex. There are a few dead springs in the surrounding area, I am wondering if this has something to do with being formed or acted on by a spring. But I don’t know why these lines would radiate from those pockets. Or why there would be pockets in the first place.
September 16, 2019
I’ve been thinking this over by myself. No one on Mindat.org of FB has made any suggestions as to what formed the rock, other than it might be gypsum. Which it is not, much too soft for gypsum. I have a reference specimen of rock gypsum, unweathered, and a self-collected piece, weathered, from Shark Tooth Hill in Kern County, California. Both those rocks are chalky and too soft to compare with the mystery rock.
Here is my working theory. The white material is calcite, a mass of which formed around several limestone rocks. At some point the mass became tumbled and rounded in the small desert wash or channel that I collected it from. Being very absorbent, the round mass picked up rainwater which would contain carbon dioxide. A weak carbonic acid would develop when the limestone reacted to that. The limestone is now eating away at the calcite, dissolving the material over the centuries.
The pockets you see are all centered on where a piece of limestone is located. The residue seen in the lines is the acidic precipitate left by this slow destructive process. Thus, that residue or the limestone does not respond to UV, being limestone and limestone related, while the calcite (the white mass or host) responds to UV as most calcite does.
Under SW UV. Forgive the “blue bleed”, a common sight when photographing glowing rocks.
— R.C. has just checked in. “If it’s calcite, no surprise. Rainwater dissolves limestone, which is calcite. Limestone typically has fractures which gradually get enlarged as rain water makes its way through. This is how cave systems form. The calcium carbonate (calcite) dissolved in the rainwater is what forms stalactites and stalagmites in caves, and it commonly fills in fractures between blocks of limestone.”
So, do we have a rock that was once a fractured piece of limestone, now with calcite accreting around the remaining pieces? In other words, this may not have been a mass of calcite to begin with, rather it was a block of limestone that started this all off. And then it transformed into what is seen today. Hmm. Still pondering. —
— Kokoweef material self-collected on mine dumps by permission. Limestone rock on top and “popcorn calcite” underneath, the calcite carbonate deposited in the form you see here. It is unknown whether this rock came from the cavern roof, its floor, or a wall.
This popcorn calcite responds weakly under SW, producing an uninteresting cream color. It does have a short but notable phosphorescence or afterglow.