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tuolumne_tradster
Trad climber
Leading Edge of North American Plate
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Jan 17, 2010 - 04:24pm PT
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I didn't have any valuable minerals in my collection but they were valuable to me because they represented memories. One of the samples was a dense, grapefruit-size mass of garnets from the Gunmetal mine. Another was a sample of the Beck Spring dolomite from Death Valley that contained a contact between stomatolites and pisolites.
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Fritz
Trad climber
Hagerman, ID
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Jan 17, 2010 - 09:35pm PT
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Minerals: I am also stumped on your last mineral posting: with the measuring stick. Nothing in granitic rock, that I have seen, matches up with your photo. Tradster guessed Sphalerite---I can't think of anything.
OK! If we are going to be tough-----here are two minerals from the same iron skarn that the Magnetite in my last question came from. Both occur very close to the Magnetite.
This one is common, but you don't see crystals or color exactly like this commonly.
This one is very-rare in crystals this size. They are frozen in marble and some are right next to Magnetite. Anyone that guesses this one: is a geologist god!
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Minerals
Social climber
The Deli
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Jan 18, 2010 - 01:44pm PT
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Yeah, Tradster, I know what you mean about rocks having sentimental value. I would be so bummed to lose my collection, or even just a few of my favorites. Large masses of garnet can be pretty cool looking. Still want to go check out the Gunmetal mine at some point here – maybe I can grab some garnet for you!
As far as my last mineral quiz, yes, the mineral is hosted in a granitic rock (of sorts) but it is also a common skarn mineral. There is one small area of the mineral in the photo that gives a clue as to what it is…
Fritz, you have a nice collection there. Great photos!
OK, I’ll give those a shot.
The first one looks like vesuvianite/idocrase, based mainly on its crystal structure, but also because of color and your description and where you found it (skarn deposit).
The second one looks like scapolite.
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Minerals
Social climber
The Deli
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Jan 18, 2010 - 02:51pm PT
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A hint on the first photo quiz on this page, the one with the vertical band:
This is not an igneous texture…
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Fritz
Trad climber
Hagerman, ID
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Jan 18, 2010 - 04:25pm PT
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Minerals: re my difficult mineral ID and your answer: The first one looks like vesuvianite/idocrase, based mainly on its crystal structure, but also because of color and your description and where you found it (skarn deposit).
That crystal does scream vesuvianite, but there is not supposed to be any at the site, and I did mention it wasn’t a typical crystal. A very close guess, though.
I’ll post a more typical crystal.
On the next photo of the crystals in marble: another good guess, but this one is very, very rare. (without refering to a geology text that covers the site: I would not have figured it out---ever.)
Here is another camera angle on the specimen.
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Minerals
Social climber
The Deli
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Jan 18, 2010 - 05:17pm PT
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Fritz, on the first mineral, I thought you meant that it usually didn’t form well-developed crystals and is usually more massive in habit. I didn’t understand that the first photo shows an atypical crystal structure/shape. Thanks.
OK, my second guess on the first mineral: apatite?
So, you are saying that the second mineral is a really weird one? Hmmmm… I’ll have a look but don’t know about that one… Your second photo does help, though.
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Fritz
Trad climber
Hagerman, ID
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Jan 18, 2010 - 05:38pm PT
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Minerals: On the first photo, go back to silicates. You were much closer on your first guess of Vesuvianite.
Here's a photo looking down on the largest crystal of the first specimen.
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Minerals
Social climber
The Deli
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Jan 18, 2010 - 05:58pm PT
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Whew… These aren’t easy or I am being retarded! I thought apatite because you mentioned that it was close to the magnetite and just read about the common occurrence of apatite with magnetite/iron ore bodies.
OK, how about diopside (pyroxene)?
And a WAG on your second mineral… manganite?
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Fritz
Trad climber
Hagerman, ID
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Jan 18, 2010 - 06:12pm PT
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Minerals: Diopside it is! As you said, identifying minerals from photos is difficult.
Second guess wasn't bad. However the mystery mineral is a mix of MG, FE, B, and Oxygen. No commercial value, and I think only of slight interest to collectors.
I like those black minerals more and more though!
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Minerals
Social climber
The Deli
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Jan 18, 2010 - 06:35pm PT
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Yeah… it is difficult! Not quite like having the sample in your hand, with a hand lens in the other…
I was thinking diopside after you said that vesuvianite was close, but for some reason it didn’t look right and I went with apatite, which made me hungry. Mmmm, mini Clif Bars…
I don’t see anything with Mg, Fe, B, and O in my text. But I thought it might have iron in it, based on the “limonite” staining and the occurrence with magnetite. Manganite is the only one in my text that was close. What mineral is it? A borate?
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Fritz
Trad climber
Hagerman, ID
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Jan 18, 2010 - 08:57pm PT
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Minerals: It is Ludwigite and is a borate.
http://www.mindat.org/min-2454.html
Only mineral collecting I have ever engaged in, where I was worried about a cornice falling on me.
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Minerals
Social climber
The Deli
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Jan 18, 2010 - 09:16pm PT
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Ludwigite? Never heard of it… but now I have. It’s not listed in my field guide to rocks and minerals or my Manual of Mineralogy, but it is listed in Hibbard’s mineralogy book, briefly. I never would have found it. Good one Fritz! I will try to come up with a few more here at some point…
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dipper
climber
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Topic Author's Reply - Jan 21, 2010 - 12:57am PT
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Folks,
I am very much enjoying all the rock talk goin' on here.
Please continue.
I have been rummaging around the terabytes and found these two.
Any takers?
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Shack
Big Wall climber
Reno NV
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Jan 21, 2010 - 01:01am PT
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That's too easy...I'll let someone else have a chance. ;]
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dipper
climber
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Topic Author's Reply - Jan 21, 2010 - 01:14am PT
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Two more, these are at the southern end of the Sierra in the Golden Trout Wilderness
Detail of the above rock
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Studly
Trad climber
WA
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Jan 21, 2010 - 01:30am PT
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are the first two photos shale and malachite?
Last photo a form of quartz perhaps?
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Minerals
Social climber
The Deli
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Jan 21, 2010 - 01:23pm PT
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Well… gotta say… Wall climbing photos and geology are a hell of a lot more interesting than silly politics and those other random subjects that seem to keep people so entertained… Oh, well.
Glad you have been enjoying this thread, Dipper, and hope that it has been helpful/educational to others as well. As climbers, I think we owe it to ourselves to know at least a little bit about the rock that we enjoy climbing on so much. And, geology is fun too!
Thanks for your post, Studly! I hope more of you will join the conversation, before Fritz and I go through our entire mineral collections! ;)
Dipper, your first photo is beautiful! I scrolled down, and for the first millisecond that I saw that photo, my brain said… flow banding in obsidian! But then my eyes saw the rest of the photo and the background… and I took a closer look at the rock. It’s certainly not obsidian! Is that the summit of a peak or near the summit? Owens Valley in the background?
The rock in the foreground looks granitic to me, based on color and the way it fractures. The banding seen on the surface of the outcrop appears to be more hydrothermal alteration along fractures/weaknesses; the “bleached” plagioclase gives the bands the lighter color. Visually speaking, this alteration seems to be accentuated by surface weathering – aside from the lighter-colored bands, the weathered surface of the rock is darker in color than the freshly broken surfaces, although I think I can just barely see the banding continue on the fresh surfaces. If the banding in the rock were due to the segregation of different colored minerals within the rock, then we would expect to see the banding continue through the rock and on the fresh surfaces, which we don’t see. I’d guess that this rock is granodiorite or diorite, based on color. The rock in the upper left of the photo is either a section of the same rock type that has not been altered or it is a dike or larger intrusion of another rock type, with the transition representing the contact between the two different rock types. The brown-colored rock in the lower right looks like some sort of metamorphic rock, based on color.
Doesn’t look like malachite in the second photo. What other green minerals have we discussed so far? How about the brownish spots just left of center and the black stuff in the lower right? I’ll leave the lichen to the bio-types.
If the sun ever decides to show itself again, I’ll take some more mineral photos to post.
OK, Shack… You keep all the answers to yourself and I promise not to tell them anything about CT scanners! :)
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Minerals
Social climber
The Deli
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Jan 21, 2010 - 01:25pm PT
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Still looking for a rock-type name and a mineral name, from my quizzes on the previous page… Or should I spill the beans?
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Klimmer
Mountain climber
San Diego
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Jan 21, 2010 - 02:40pm PT
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Ok, the image above with "Banding" pattern is in the Sierras. I can see the volcanic cinder cones on the Eastside of Owens Valley N. of Independance and S. of Big Pine. Hey, location helps.
The banding as Minerals has pointed out doesn't look like it is through the rock. I can't see the banding pattern on the broken faces facing the camera. So, is it just a surface pattern? Don't know. Hard to tell.
Flow Banding does happen in igneous rock but kinda rare. If it is igneous rock with flow banding, then it is an unusual phenomenon. And the igneous rock would be . . . ahhhh, hold on a minute, looking up table on classification of igneous rocks. Ok, my best stab in the dark would be: Igneous, Intermediate, Extrusive with flow banding, texture looks fine-grained, so = Andesite. Edit: ok, if it is intrusive then it would be Diorite.
Could it be metamorphic? Hard to tell. Can't touch a picture. Hard to figure out . . .
3rd image of unusual cleavage pattern on boulder in the Sierras? When all else fails throw-out Plagioclase, Feldspar! It is bound to be the answer eventually. Lite in color minerals are hard to distinguish if you can't look at it, hold it, test it.
Ok, so how bad did I do?
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Studly
Trad climber
WA
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Jan 21, 2010 - 02:47pm PT
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I am pretty ignorant about rock identification, would love to know more. Klimmer you said the top photo might be andesite. I climb on andesite up here in the Columbia River Gorge area a ton, and that looks like no andesite I have ever seen. Could it be that completely different? As rarely does andesite appear to have regular patterning, it is more random and weathers completely different then that phots, as least in my experience up here.
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