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fear
Ice climber
hartford, ct
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So what did they presumably mine there? Gold?
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - Feb 7, 2017 - 06:32pm PT
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Albatross! Thanks, I appreciate the complement.
Fear: Based on my going over the mine dumps looking for collectable specimens, I was slightly amazed at how little valuable ore I found. The local contact zones mostly produced copper minerals & lead minerals & darn little gold.
I've rarely found a remote pre-1900 mine with less ore left on the dump. It appears the last mine manager soon figured out that if the mine ever had valuable ore, it was all gone.
From 1860 on, many western U.S. mine promoters mined more income from investors in the eastern U.S. & England, than they mined out of the ground.
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hooblie
climber
from out where the anecdotes roam
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - Feb 14, 2017 - 09:12am PT
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Heidi has a long-term collection of natural rock hearts, but I found a few larger ones to share too.
Bigger Heidi rock heart.
And another.
Maui breaking wave sea-cliff heart & Heidi
Joshua Tree has a big heart.
Hawaii tide-pool heart.
Australia coral heart
Maine art-heart.
Best wishes for a Rocky Valentines Day!
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jonnyrig
climber
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Feb 14, 2017 - 10:04am PT
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Rocks are fun. I like rocks. More than I like people.
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - Feb 14, 2017 - 12:25pm PT
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johnnyrig. Yep! Rocks are more solid than most people, except for the flaky or schisty ones.
And I agree, most likely pyrite.
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mouse from merced
Trad climber
The finger of fate, my friends, is fickle.
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Feb 14, 2017 - 02:34pm PT
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"Spurious non-permutaceous diaclassic displacement oriented to the garblebasic plane."
:0)
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - Mar 28, 2017 - 05:08pm PT
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Tourmaline isn't just tourmaline. Instead geologists call it a group & divide it into 6 different members. But let's make it easy & just think of it as black tourmaline = Schorl, colored tourmaline = Elbaite, & to keep the geologists somewhat calm, I'll add brown tourmaline = Dravite
A lot of gem quality Elbaite has come out of the mountains east of San Diego, but I don't have any specimens.
Idaho is somewhat lacking in tourmaline & I must confess to not yet having found any, but I'm working on it.
In fact, the only tourmaline I've ever found is this river cobble with small pieces of Schorl in it. I dragged it home from a 10,000' high stream in Mustang Nepal.
A friend gave me this nicer Schorl in Mica schist specimen, that she found in the Everest area of Nepal.
A few years back I was quite taken with specimens of Brazilian Elbaite that had intergrown with quartz crystals. I broke down & bought some.
Here's a closeup of that crystal.
Here's a closeup of another quartz crystal with some beautiful tourmaline inclusions.
Multi-colored tourmalines are commonly called Watermelon tourmalines & my specimen in not of gem-quality, but does include a quartz crystal as its host.
Elbaite tourmaline also comes in pleasing pink shades.
At the Tucson Gem & Mineral Show, Elbaite tourmalines to die for, are everywhere.
Here's a couple watermelon tourmalines I found interesting in Tucson.
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - May 2, 2017 - 10:02am PT
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We visited the new Bear's Ears National Monument last week & I thought I should share some rocks from there.
The rounded Manos aka grinding stones are some type of granitic rock. There is no granite in the area, but there are plenty of granitic cobbles along the San Juan River 20 miles south. These were carried to this site around 1000 years ago, since the local sandstone does not grind corn & seeds in a satisfactory way.
We of course left them in place.
There was a nice coat of "desert varnish" on this chunk of sandstone. The black-patina provided a nice canvas for art a long time in the past.
Some of the local sandstone (I think it's named Cedar Mesa Sandstone)
shows great cross-bedding.
In other places the sandstone shows nice uneven bedding.
A few miles to the west in a canyon bottom, some of the sandstone is very photogenic.
And don't forget!
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Reilly
Mountain climber
The Other Monrovia- CA
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Dig the tourmaline crystals! That horizontal pictograph is kind of odd,
don't you think? Seems to have survived a lot better than I would expect.
Found these strange mini volcanos near to where you were.
Never seen nuthin like 'em on sandstone.
Oh, here's a real rock...
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - May 2, 2017 - 07:06pm PT
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Reilly! Re your comments:
That horizontal pictograph is kind of odd,
don't you think? Seems to have survived a lot better than I would expect.
Found these strange mini volcanos near to where you were.
Never seen nuthin like 'em on sandstone.
That petroglyph has about a 30 degree angle, but is south facing & unprotected from weathering. I think that black "desert varnish" is darn weather resistant.
I don't remember seeing mini-volcanos like those. Spiders, centipedes, lizards, or snakes,-----or small space aliens?
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - May 3, 2017 - 07:47pm PT
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On our last afternoon hike, east of Torrey Utah, we hiked up a wide drainage that narrowed into a slot canyon.
We finally hit a deep pour-off pool that Jerry briefly tried to chimney.
The sandstone had a lot of, iron/ manganese?, inclusions in it, that I attempted to relate to fossilized algae. No-one believed me.
Any professional opinions?
Edit! Per my next post & post #261 in this thread, the above photo is of an iron concretion & it not a fossil.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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possibly desert varnish
Desert varnish consists of clays and other particles cemented to rock surfaces by manganese emplaced and oxidized by bacteria living there. It is produced by the physiological activities of microorganisms which are able to take manganese out of the environment, then oxidize and emplace it onto rock surfaces. These microorganisms live on most rock surfaces and may be able to use both organic and inorganic nutrition sources. These manganese-oxidizing microorganisms thrive in deserts and appear to fill an environmental niche unfit for faster growing organisms which feed only on organic materials. https://www.nps.gov/cany/learn/nature/desertvarnish.htm
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - May 4, 2017 - 08:06am PT
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After some more research on the subject of the strange iron concretions we found, I searched out a publication on the subject that is written for the public.
Desert Varnish & iron concretions, like those I found, in what is probably the Navajo Sandstone formation, are formed in different ways.
Navajo Sandstone iron Concretions are:
• Natural balls and other shapes formed in a porous sandstone.
• Made up of hematite (iron oxide) cement that precipitates around quartz sand grains.
• Likely comes from iron that was bleached out of red sandstone.
• Formed from the mixing of different fluids: reducing water carrying iron
interacted with oxidizing water that induced the iron precipitation.
• More resistant to weathering (i.e., harder) than the quartz sandstone host rock.
• Unusual and can look “out of this world,” but are formed by Earth processes over many tens of millions of years.
Iron concretions are also known by other names (not inclusive) such as:
• Hematite or iron nodules
• Iron sandstone balls
• Moki or moqui (term used by early Spanish) marbles
This illustration is a little blurry in the pdf I copied it from, for some reason
For much more on the subject, here's the link.
http://files.geology.utah.gov/online/pdf/pi-77.pdf
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Reilly
Mountain climber
The Other Monrovia- CA
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TT, what's yer take on my 'mini volcanos'?
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Craig Fry
Trad climber
So Cal.
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The 'mini volcanos' are just areas of harder sandstone that has eroded slower than the surrounding rock.
They look like they may be enriched with iron, which would give them the rusty color.
They are very common in the Laguna Hills Sandstone. The Mt. Bike trails that go over solid sandstone are covered with them which makes for somewhat treacherous terrain trying to avoid the big protuberances pointing every direction.
Some of my Tourmaline
I collect single crystal specimens, so they don't have any matrix on them.
The Matrix specimens are usually way more expensive.
Those prices of the tourmalines from the Tucson show by Fritz are outrageous!
I usually pay wholesale of look for super good deals.
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skcreidc
Social climber
SD, CA
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Yes Fritz, inclusions are what you find in igneous rocks whereas concretions are in sedimentary rocks, generally speaking. As geologist's understand the process now, concretions are typically formed during the early phases of diagenesis (the physical and chemical changes occurring during the conversion of sediment to a sedimentary rock). The chemical precipitation of minerals within the pore spaces of sediment seem to be dominated by oxidation-reduction reactions. One of the most common factors in this process is the presence of organic carbon in the sediment. The oxidation of organic carbon is bacterially driven and takes the water from oxidizing into reducing via aerobic, nitrate reduction, sulfate reduction, and finally methanogenesis if the O-carbon content is high enough. So, if you have red (iron) cementation, you are still under aerobic conditions (free O2 in the water). Nitrate and sulfate reduction tend to lead to green (reduced iron) colors, whereas methanogenesis typically is very dark gray or black.
The concretions tend to form where these oxygenated and reduced waters can mix. Having something like a buried branch (organic carbon) can be the nucleus for such reactions to occur, as in the case of Reilly's mini volcanoes, causing a higher density of precipitation. There are a number of classic cases of fossils being inside of concretions; another case for organic carbon being important in the process at least sometimes.
• Unusual and can look “out of this world,” but are formed by Earth processes over many tens of millions of years.
This statement is an assumption based on an older prevalent geologic philosophy which I think really needs to be reevaluated. The Linda Vista Formation of San Diego (Torrey Pines) is highly cemented with Iron oxide and is famous for it's iron marbles weathering out of the rock. The unit is no older than 1 million years.
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Fritz
Social climber
Choss Creek, ID
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Topic Author's Reply - May 4, 2017 - 11:24am PT
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skicridc! Thanks for chimming in.
DMT! Per you statement: I can't help but think - those late 1800s miners were tough bastards, and mostly fools (with other peoples' money).
I've often thought the same, expecially when I find some large & heavy machinery at old mines high in the mountains, that never had a road to them.
The 2' diameter iron wheels probably weigh between 600 & 1000 lbs each. It's the upper part of a tramway system dating to the 1880's. There's not even a trail to the mine, which sets above cliffs at around 10,000'.
In this photo, the mine with the above machinery is right of & just below the snowfield.
And in this photo, the mine is pointed out by the red arrow.
I think folks were tougher then.
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Craig Fry
Trad climber
So Cal.
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There are still many tough miners out there.....
You should see the images I see from third world country mining
barefooted, a towel wrapped around their private parts, equipped with a hammer and pick
strong men are mixed with children and women, they slink down homemade broken ladders into dark pits for a day or two of mining for a couple cents a day
It's the only work they can get
back before pollution science, miners would last two years max after working the arsenic furnaces,
and with a 100 more ways to be killed
mining was the most dangerous work you could do
and still is for many
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