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Jaybro
Social climber
wuz real!
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They just don't make rocks like that anymore...
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scuffy b
climber
On the dock in the dark
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well, sometimes my dumbness surprises me.
Where's the doggone K in that chart?
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scuffy b
climber
On the dock in the dark
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okey-dokey, thanks, Wes.
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GOclimb
Trad climber
Boston, MA
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Wes - sounds like I should go back to my earlier explanation, that the Acadia Granite around Otter and Precipice Cliffs gets its deep pink (maybe verging on purple when weathered) from all the Alkali/K Feldspar - the pink stuff in your photo. In other words, it is the bottom left stuff like I thought, not bottom right.
GO
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drunkenmaster
Social climber
santa rosa
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Gneiss Schist Minerals! Thanks. More inforumative posts like this are much needed - yes.
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Minerals
Social climber
The Deli
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Good stuff! Nice to see a few more of you chiming in.
Don’t know about that, Jaybro. My knowledge of granites is pretty much limited to the Sierra Nevada and Northern Nevada.
Wes, I’ve never really thought about the patina at the Buttermilks but that is an interesting question. What’s the Dorn story? Your thoughts?
There is granite in Utah…?
GOclimb, you’ve got it right; the rock that you climb on lies in the lower left side of the diagram. From your last photo (nice joints, btw) it appears that there are a few lighter spots – this is most likely quartz but could also be plagioclase. So, the rock is probably granite, but could be an alkali feldspar granite, or even something closer to the syenite field. Looks like nice stuff.
Well, we might as well throw in a little mineralogy so that we have a few building blocks to make granitic rock…
Common minerals found in granitic rock:
 Quartz – SiO2
Potassium feldspar (Orthoclase) – KAlSi3O8
Plagioclase feldspar (Albite – Anorthite) – NaAlSi3O8 – CaAlSi3O8
Biotite – K(Mg,Fe)3(Al,Fe)SiO10(OH,F)2
Hornblende – (Ca,Na)2-3(Mg,Fe+2,Fe+3,Al)5(Al,Si)8O22(OH)2
Titanite – CaTiSiO5
Magnetite – Fe3O4
Apatite – Ca5(PO4,CO3)3(F,OH,Cl)
Garnet (Almandine) – Fe3Al2(SiO4)3
Muscovite – KAl2(AlSi3)O10(OH)2
Ilmenite – FeTiO3
Monazite – (Ce,La,Nd,Th)PO4
Zircon – ZrSiO4
Tourmaline – (Na,Ca)(Mg,Fe+2,Fe+3,Al,Mn,Li)3Al6(BO3)3(Si6O18)(OH,F)4
Wes mentioned earlier that plagioclase feldspar is a solid solution, with albite and anorthite as the end members. Labradorite is one of the intermediate varieties of plagioclase and is commonly seen as the iridescent blue-colored mineral found in some granitic countertops. Where’s our countertop man, Skully?
Time to dig up some photo examples…
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Minerals
Social climber
The Deli
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Ok, I have a question for you guys. While out in the desert last week, on the east side of Winnemucca dry lake, I stumbled across this pothole in what I think is bedrock (although it is possible that it is a boulder). It threw me for a loop! The inside of the pothole is rounded and the surface is polished smooth, just like a pothole that you would see in a river or glaciated areas, like Tuolumne. There is obviously no water in the area now, however this outcrop would have been submerged during the high-stand of Lake Lahontan approximately 13,000 years ago. The outcrop does not lie in a drainage, but on more of a slight ridge on a slope below the main outcrop of bedrock that forms the mountainside.
The pothole. The polished areas are rust-brown in color; in some areas, such as behind the hammer handle, the polish has weathered away. There are two rounded scoops on the top rim, one at the back (where the darker patches of rock are) and the other on the right side. The light-colored section on the left is part of a pegmatite dike.
Another view – the outcrop looks more like bedrock than a detached boulder. No?
The pothole is located on the short slope below the obvious bedrock, just left of center in the photo. Also note series of felsic dikes.
What do you think? Gstock?
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scuffy b
climber
On the dock in the dark
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Is there more of that polish (regardless of shape) on any of
the bedrock around there?
Have you ever seen features like that which you could attribute
to wave-related erosion in a lake?
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Minerals
Social climber
The Deli
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Scuffy, I didn’t notice any other polished surfaces; the rock surfaces are pretty rough in this area. That’s the thing… I generally think of potholes as forming from the abrasive action of cobbles swirling around in rapidly moving water – in a river. How would this be possible in a shoreline environment? I dunno.
Interesting idea, Wes. Keep us posted on your findings. What was the original Dorn idea?
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Jaybro
Social climber
wuz real!
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Isn't a lot of (funky) black Patina in desert places, IC, the Swell, Redrocks, volcanic tablelands, etc, thought to maybe be a product of a sort of evaporative/leaching/constituent mineral/etc migration with possible bio agent contribution kinda deal? Clearly moisture dependent, but media (almost) agnostic?
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scuffy b
climber
On the dock in the dark
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It seems so unlikely, Minerals.
Just thought I'd have to put it out there.
Maybe in several-to-many miles of shoreline,
a spot like that might develop?
Lahontan had a pretty big shoreline. Maybe you found
a tiny jackpot. Check the next couple hundred miles?
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Jaybro
Social climber
wuz real!
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Misnomers abound.
the Phx Rock guide with the ape on the cover refers to the "Solution pockets" in the Queen creek, volcanic rock.
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Minerals
Social climber
The Deli
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Dec 12, 2008 - 12:53pm PT
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Thanks for the Dorn info, Wes. That sounds like some weird stuff… with bacteria and all…
Yeah, Scuffy. Maybe that pothole is a rarity. Who knows… I just thought that it would be fun to throw it out here. It’s definitely not a solution pocket – I’ve seen many of them and this pothole is polished on the inside – too smooth and rounded to be a solution pocket. This thing sure looks like it formed in a fluvial environment to me… But how???
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Minerals
Social climber
The Deli
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Dec 12, 2008 - 12:55pm PT
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Here’s an easier one…
Name the four basic rock types in this outcrop, listing them in relative order, from oldest to youngest.
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scuffy b
climber
On the dock in the dark
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Dec 12, 2008 - 02:09pm PT
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upper left volcanic youngest,
pale center,
dark lower center,
grey lower left oldest?
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KyleO
Ice climber
Calgary, AB
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Dec 13, 2008 - 02:42am PT
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Youngest
Erosion creating surrounding clasts
Injection of light colored igneous intrusion
Folding event (axial trace 45* up to right)
Dark metamorphic rock (amphibolite)
Greenschist metamorphic rock
Oldest
Sweeet outcrop. Not easy at all!!
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Dr. Rock
Ice climber
http://tinyurl.com/4oa5br
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Dec 14, 2008 - 01:11pm PT
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You ever heard of "The Lisping Geologist?"
It's a little routine I worked up out of boredome one day while sitting in on Dr Ramsey's Geo class at Sac City with the little lady.
We were drinkin 10 AM wine coolers in the back row as usual (co-dep), use the sport bottles, anyway, this guy had a slight lisp, so anything with an S.
Observe:
"Ssscchhist, Ssscccchlate and Shhhherrerpintine were formed from ssstalagmite intrusions of ssssedimentary rock.
Ssssshubduction zones formed by sssshhpheroidal weathering were studied using ssshheismic tomography have been known to contain elements of ssshhilicon oxygen tetrahedron.
Any quesssssshhtionssshhons?"
You get the point.
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Dr. Rock
Ice climber
http://tinyurl.com/4oa5br
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Dec 14, 2008 - 03:35pm PT
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Applications:
Pink Granite is used in the machine shop as a level surface.
Amorphous Silica has just recently been used in high end audio transformers, see search Lundahl.
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Dr. Rock
Ice climber
http://tinyurl.com/4oa5br
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Dec 14, 2008 - 03:35pm PT
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Applications:
Pink Granite is used in the machine shop as a level surface.
Amorphous Silica has just recently been used in high end audio transformer laminations, search Lundahl.
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