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Jaybro
Social climber
Wolf City, Wyoming
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Jan 10, 2010 - 12:56am PT
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Hoh yeah, Bryan, now we're talkin'!
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 01:04am PT
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Cool, Jaybro!
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 01:05am PT
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A simple quiz…
What’s this and when?
Location
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 01:15am PT
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And a related subject…
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Fritz
Trad climber
Hagerman, ID
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Jan 10, 2010 - 01:28am PT
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Minerals: I will jump on this one since "I seen it."
It is a "big" earthquake scarp (fault) line S. of Winnemucca. I can't remember the date---but 1950’s??
It is very similar to the scarp line near Mt. Borah in Idaho from the 7.8 earthquake in the early 1980’s. A women out hunting was actually on the fault line for that one and got to fall back as her turf stayed more or less even and the land next to her ripped up 12 feet.
Re. my photos and assertions that the garnet in the Sawtooths is spessartine: I am quoting my geologist betters. I own several U of Idaho publications that deal with Sawtooth geology and none mention any garnet other than spessartine.
However, as you know----“there is always something new to see.”
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 01:59am PT
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Right on, Fritz! You got it! Yeah, that Borah Peak scarp is cool too! Got photos of it here somewhere.
The above photos are from north of the Dixie Valley and Fairview Peak faults systems - 1954 rupture.
http://www.bssaonline.org/cgi/content/abstract/86/3/761
http://www.seismo.unr.edu/ftp/pub/louie/dixie/
Well, it sounds like your sample is all spessartine. Do you think the change in color is from a trace element of sorts, like the uranium in your quartz crystal? Or just a different color of the mineral? Interesting that there is no mention of any other varieties of garnet in the Sawtooths.
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dipper
climber
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Topic Author's Reply - Jan 10, 2010 - 02:27am PT
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Some granite
Mt. Tyndall on the skyline
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 02:55am PT
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Silicified fault breccia
What is the dull-grey mineral?
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Fritz
Trad climber
Hagerman, ID
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Jan 10, 2010 - 01:47pm PT
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Minerals: Re. my spessartine garnet photos from the Sawtooths, I have been quoting from "Idaho Minerals" by Lanny Ream. He seems to have his details down quite well. However, this morning I went digging thru old publications and find that the most detailed: "Reconnaissance Geology of the Sawtooth Range," only says garnets.
So----since the photo was taken in an area that is climber's terrain, maybe it does show a transition from spessartine to almadine. Then again, most spessartine we see as mineral specimens is that nice light orange color. You can see dark colors in spessartine at the minedat.org website. http://www.mindat.org/photosearch.php?cform_is_valid=1&frm_id=mls&minname=spessartine®ion=all&text=&otype=0&stype=0&phototype=M&mtype=0&sort=&submit_mls=Search&phototypeo=M&go=1&cf_mls_page=2
Spider Savage: Yeh, I have a Forestry degree from U of I. I was never too enthused about lava flows. The "channeled scablands" in E. Washington, caused by "glacial lake Missoula," were pretty cool to look at.
I bumped into a geologist friend that works for Idaho Geological Survey a couple years back. He was in this area mapping volcanic flows. We invited him to dinner and he talked for hours about local volcanos and flows. From our back yard he could name the main flow that makes cliffs near our "ranchette." He had mapped it to a volcano that doesn't look like much, that is 20 miles away. It kinda made that basalt stuff a little more interesting to me.
However! Speaking of garnets! I have warmed up to skarns during the last few years. I found some cool garnets in one this summer. It is on the south edge of the 7 Devils range in Idaho and is a inactive copper-mining area. In this case a few big chunks of limestone were floated and metamorphized by igneous intrusions.
There are two types of garnet in the area: andradite and grossular. Unfortunately, I can't be sure which is which? There is also lots of epidote and is some cases the garnets may have been altered to epidote. All very confusing, but fun to look at.
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Jaybro
Social climber
Wolf City, Wyoming
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Jan 10, 2010 - 01:52pm PT
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cross post
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 07:22pm PT
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Jaybro – Ha! Nice eyeball in the grass…
Hey, Fritz… Really nice photos of the garnet! Those are great! Your first photo shows the “diamond-shaped” faces of a garnet crystal. And I see what you mean about the different colors of spessartine, based on your link. I need to go get my textbooks out of storage to be able to discuss this in much more detail. There has got to be a reason for the difference in color in garnet and I’m still thinking that is has to do with composition. From a pocket guide to rocks and minerals, grossular: “…cinnamon-brown to orange when containing iron (hessonite variety) and magnificent emerald-green with chromium (known commercially as tsavorite).”
The darker garnet in your first photo is probably andradite, like you say, and maybe the orange-colored garnet in the other photos is hessonite??? I need my textbooks.
As far as epidote goes, I see the green (epidote) in your photos but think that all of the crystals that are garnet-shaped are garnet – just different colored. I’ve never seen epidote that has replaced garnet. A mineral that is chemically altered to another mineral but still retains its original crystal shape is referred to as a pseudomorph.
Pseudomorph:
http://en.wikipedia.org/wiki/Pseudomorph
Here’s some more info on garnets, but it doesn’t make up for a mineralogy text…
Garnet:
http://en.wikipedia.org/wiki/Garnet
Here’s one from last Wednesday, at a skarn deposit in Northern Nevada that was mined for copper (chalcopyrite).
Calcite (white), epidote (green), and garnet (brown – andradite or grossular)
Photo by Kait
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dipper
climber
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Topic Author's Reply - Jan 10, 2010 - 07:35pm PT
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A few more images to marvel at. These are on the road out to Battery Spencer above the Golden Gate Bridge.
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 07:46pm PT
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Chevron folds in metachert! Nice, Dipper!
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 10:50pm PT
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What is the green mineral?
Any guesses on the dull-grey mineral yet?
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Jaybro
Social climber
Wolf City, Wyoming
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Jan 10, 2010 - 10:55pm PT
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Serpentine on it's way to asbestos?
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 11:47pm PT
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Hint: It’s in Nevada and can be of economic interest.
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Minerals
Social climber
The Deli
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Jan 10, 2010 - 11:48pm PT
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More Tertiary seds
Photo by Kait
Megacrysts...
...and enclaves
Granite
Metamorphic rock
Squish
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Fritz
Trad climber
Hagerman, ID
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Jan 11, 2010 - 12:24am PT
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Minerals: Re your quiz questions. The grey stuff doesn't have that galena look to it, and otherwise I can't guess.
For the green: obviously a copper mineral, and I'll go with the obvious --- Malachite.
On your most recent post, last photo, of course I have to comment: Gneiss picture!
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