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Spider Savage
Mountain climber
The shaggy fringe of Los Angeles
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I'm into formations and common stones.
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MisterE
Gym climber
Being In Sierra Happy Of Place
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This whole idea is so random, I just might have to get my hate on to freeze this thread...
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Fritz
Trad climber
Choss Creek, ID
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Topic Author's Reply - Sep 1, 2015 - 08:38pm PT
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Schist! I have been a neglectful thread steward!
First! Thanks for all that post good rocks!
Second! I must say: fuk off on your thread jealousy, Mr. E.!
I have been having soooooo-much outdoor fun in my first year of retirement, that I have not been posting rocks on Tuesday. That will likely change in October.
Until then, here's some photos from one of many Idaho & northern Nevada high mountain hikes to old mines this summer. This one was last week.
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Fritz
Trad climber
Choss Creek, ID
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Topic Author's Reply - Oct 6, 2015 - 11:27am PT
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Nice Rocks folks. Brave Cowboy? What the hell is that really, red, rock? Cinnabar?
I was combining climbing with mineral collecting last June, & was balanced on a couple OK footholds, about 6 feet above a 60 degree talus slope, using a chisel & hammer to cut out a chunk of rock with the largest garnets I’ve ever found. It took a few minutes of hammering, and along the way I lost concentration - - WHAM! I haven’t smacked my thumb as good as that since I was in my 20’s placing bolts on runout slabs. This is the specimen & my thumb about two-weeks later. I worried that I was going to lose the nail.
And today, almost four months later.
There were some nice smaller, but shinier garnets there too.
On the brighter side, although I got held up a while by a cattle-drive on the way out of the mountains, the cowgirls liked me.
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thebravecowboy
climber
The Good Places
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Hey Fritz! That is some fatty garnet! And I hear you on the inherent sketch of field geology - still picking splinters outta my hands and feet, nursing a similarly wounded digit (flyrock, not hammer-strike, thankfully).
It's banded iron formation from the southern edge of the midcontinent rift. Definitely older than 1000 My. Magnetite and hematite compose the bands, and what a cool structural history they show! I picked it up along the Presque Isle River last week. It is a detrital component of the units that I study.
Sure is pretty.
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hooblie
climber
from out where the anecdotes roam
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staking out the high ground in the show me your discus event ...
bring on the remarkably durable sculpted orange shag
and furtive goathead lurkin' turf challenge any time
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Fritz
Trad climber
Choss Creek, ID
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Topic Author's Reply - Oct 20, 2015 - 09:25am PT
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Pyrite, FeS2 is defined as being in the Isometric crystal system, but has eleven different crystal forms.
(how do it know, which form to crystallize in?)
The 3 most common pyrite crystal forms are: Cubic, Octahedral, & dodecahedral, also known as Pyritohedral.
The only crystal form of pyrite I have found is cubic & I've found a lot of small cubic pyrite crystals in Idaho & Nevada.
Heidi bought this one at a long-ago Tucson Gem & Mineral show.
Here's a nice specimen from Peru of Pyritohedral pyrite.
And an Octahedral pyrite from Peru.
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donini
Trad climber
Ouray, Colorado
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Oct 20, 2015 - 09:30am PT
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Thanks for brightening up my day. It's dark and grey here with a cold rain falling.....even the cats don't want to go out.
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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Oct 20, 2015 - 09:43am PT
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Various forms of halite from Bavarian salt mines on display at the Deutsches Museum
Halite from the Salzbergwerk Mine in Berchtesgaden
Granite cairns at the top of the Krimmler Wasserfalle in Austria
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Fritz
Trad climber
Choss Creek, ID
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Topic Author's Reply - Oct 27, 2015 - 05:30pm PT
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TT! Nice salty rocks!
Idaho has quite a few contact-metamorphic deposits where the slightly collectable mineral Diopside (CaMgSi2O6) can be found as small greenish crystals. I lucked out a few years back & surface collected what may be the state record Diopside crystal.
I have found much smaller, but much more pleasantly green Diopside crystals at two other Idaho locations.
This one is from summer 2014. The crystals are 1/4" long or less and are in calcite.
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thebravecowboy
climber
The Good Places
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Oct 27, 2015 - 06:17pm PT
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good stuff as always Fritz
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StahlBro
Trad climber
San Diego, CA
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Oct 27, 2015 - 08:53pm PT
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thebravecowboy
climber
The Good Places
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Oct 27, 2015 - 08:56pm PT
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nice VotG intercalation of arkosic mudrock and ferruginous Ss, Stahlbro.
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Flip Flop
climber
Earth Planet, Universe
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Oct 27, 2015 - 09:39pm PT
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Fritz
Trad climber
Choss Creek, ID
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Topic Author's Reply - Nov 3, 2015 - 01:03pm PT
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Ammonites and/or Ammonoids are my favorite fossil. I was given one when I was a teenager, but I never found one until I was in my mid-30’s.
Ammonoids were a marine mollusk, fairly closely related to squids, except they grew an external shell. They enjoyed a long & diverse existence as a subclass Ammonoidea of the class Cephalopoda, with the first Ammonoids showing up in the fossil record around 400 million years ago & then finally going extinct in the Cretaceous Extinction about 66 million years ago.
Size wise, Ammonoids ranged from darn small to a few specimens found in the U.S. that are up to 4’ in diameter. The biggest intact Ammonoid I’ve found is about 8” in diameter. Ammonoids are important index fossils because of their wide geographic distribution in shallow marine waters, rapid evolution, and easily recognizable features.
There are a lot of fossil Ammonoids in museums & collections, & a lot still to be found. So far, the BLM & Forest Service have not made collecting them on government lands illegal. There are also many different species of Ammonoids, with some from the Cretaceous having quite fanciful shells.
Ammonoid molds & casts. All the above Ammonoids are casts of Ammonoid shells, that were covered by mud, rotted away, & were then replaced with minerals. A mold preserves a negative imprint of the surface, while a cast preserves the external form of the organism. In a few places the original Ammonoid shells have survived the process and are preserved.
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