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ale_capone
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PostTue Aug 28, 2018 9:38 am 
you are doppleganging my thoughts!

i think its some type of chalcedony, with lots of random minerals, that just happens to look like wood. possibly a casting.
after exemaning another couple pieces of rock from the same area, im finding much of the same...

the bulk of the of it is translucent, ranging from clear, yellow. orange, amber, almost red, purple and blue, and some of those green needle gems.. (mostly the neutral colors though).

looks cool when i shine a lite through, or even better when i was dry cutting a large piece in half.


i am curious about what looks like hollow tubes ive noticed in zoomed photos. keeping with the imagination theme...

prehistoric termites

same tubes, unpolished side.


brush buffalo.  sorry for the confusion, and my less then helpful photos. you would probably to do better hands on, with a loup.

only the calcite foamed. mostly the large bit in the mouth, but also from other little nooks...
*at that point, i was just trying to clean off the dirt and surface schist.

i just removed it from a 2 day soaking in oxalate acid. what ever it is, im enjoying the process of finding there is more there then i thought.

a little treasure hiding under the calcite...so like you stated, its most likely the calcite formed later. also, much of what apears to be calcite in the mouth, seems to a conglomerate of quartz and other stuff held together by calcite.. I think it was a cache of prehistoric nuts. wink.gif

many minerals.. I cant tell if they are purple, or metallic..i also think that orange spec is natural.

while it cleaned quite a bit of the exterior oxidation, it did little to nothing to the overall color. if anything, it brought ought some more colors. now seeing some purple. I suspect this was the nest of some type of small bird, as evident by the purple bird shaped skull..


i hope i posted the right photos, and they are somewhat helpful. but now that I look at the 2 previous ones, and some others, im almost certain that it's just a rock hard ham.

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Brushbuffalo
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PostMon Jul 29, 2019 5:20 pm 
Keep 'em coming, people!
You must be seeing lots of rocks, minerals, and landforms out there, between swatting the skeeters. vent.gif

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xman_reborn
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PostMon Jul 29, 2019 6:25 pm 
Here's one that you can't miss on the Bald Eagle trail, Glacier Peak Wilderness. Between June Mtn and Spring camp. It's an awkward part of the trail that takes some careful footwork around it. I couldn't really get a shot from further back. Cool rock formation. From a few years ago.

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Brushbuffalo
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PostMon Jul 29, 2019 9:40 pm 
Thanks for your post!
The layering is probably foliation and it looks fine- grained. I'm guessing it is phyllite, a low grade metamorphic rock, but I will check and revise if needed.

Edit: change my guess!  The geologic map for that area indicates the rock of June Mountain is the Nason migmatitic gneiss, a very high grade metamorphic rock. Looking closer at your picture, it does appear to be coarse-grained and is quite variable  ( migmatite means 'mixed rock', mixed in that some components of t HF e parent rock partially melted and are properly igneous).
This is yet another one I want to see from 6" away.

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Tom
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PostTue Oct 01, 2019 10:18 pm 
Saw quite a few of these rocks at Upper Kendal Peak Lake today.  Curious about the divots which seem to relate to the long and relatively straight scarring.


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Brushbuffalo
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PostWed Oct 02, 2019 8:56 am 
I checked the Geologic Map of the North Cascade Range and  although the scale is small there is a unit mapped as 'Tev' near Kendall Lakes.
Tev is " volcanic rocks, (early Oligocene and Eocene), described as "mostly basalt and rhyolite flows, breccia, and tuff intermixed with some sandstone and conglomerate."
Although not specific for this particular specimen, it also isn't conflicting.
My thought is the rock is volcanic, probably andesitic/basaltic in composition with some angular rock fragments and phenocrysts of plagioclase [ light- colored larger crystals].
The most interesting features are the lined- up cavities. I interpret those as vesicles ( gas bubbles), and the alignment is probably a flow- banding structure.  If you look closely you will see how many of the vesicles are stretched and parallel, further indicating movement while still in a plastic state.  It is unusual to have them in bands rather than more uniformly or randomly distributed
As Doppelganger notes, these two pieces were quite likely transported at least a short distance from their bedrock source. In cases like this I try if time allows to locate a bedrock source.
This is a fabulous rock! I would surely collect a piece where it is legal to do so.

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Tom
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PostWed Oct 02, 2019 1:05 pm 
Thanks for the info.  You can see a smaller rock in the first image above that appears to have broken off the larger rock.  Not sure if it was small enough to carry out (the larger rock was probably 6').  Next time I go up there I'll check to see if the various rocks piece together.  My recollection is there were quite a few of them scattered below the talus which I believe may be an inlet early season.  This area of the lake is normally under water before the level drops significantly later in season.

BTW, here's another rock in the vicinity.  Not sure if it's the same type of rock but it has large divots as well.  Perhaps those other rocks broke off this one or the rock further out in the lake which has pieces broken off.

Note rock to lower right
Note rock to lower right

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Brushbuffalo
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PostWed Oct 02, 2019 3:20 pm 
The rock in the lower right of your final picture appears to be a more typical vesicular andesite without the flow banding.

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Brushbuffalo
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PostFri Oct 04, 2019 3:56 pm 
Doppelganger wrote:
seem to be some interestingly flat rock surfaces

Flat [ planar] rock surfaces aren't rare. In the majority of cases the planes are joint surfaces. Joints are fractures similar in their planar nature to faults; joints are cracks without differential movement on opposite sides of the joint, while faults show displacement on opposite sides.

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Brushwork
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PostFri Oct 04, 2019 9:24 pm 
Already gone over my head..
or, iím getting to old to actually think.   Boy, that is scary...,

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Sculpin
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PostSat Oct 05, 2019 9:34 am 
Found this one about 1/4 mile northeast of Windy Pass Tarn, on the west slopes of Mt. Cashmere:


The greenish rock that comprises the bottom layer was soft and frangible with no obvious crystallographic features.  The metallic green stuff at the top was in fine layers like mica, stacked like a deck of cards.

I have not perused a geological map but can attest that the geology is up there is very complicated and local.

The image was taken in my front yard.    biggrin.gif

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Brushbuffalo
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PostSat Oct 05, 2019 12:32 pm 
That's definitely a penny!
Oh, you mean the rock! biggrin.gif

( when I don't know I try lame humor).

Sculpin wrote:
geology is up there is very complicated and local.

I am guessing this is a fragment of a contact metamorphic rock associated with the margin of one of the intrusions in that area. Too much in this sample for me to be definitive without holding  it in hand and also by  looking around carefully in the field. Sorry. And thanks for the penny for scale.

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NorthBen
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PostSat Apr 11, 2020 10:35 am 

Noticed this rock near Teneriffe Falls (outside North Bend) and recall seeing similar rocks near the summit of Mount Teneriffe along the official trail that approaches from the west.

Any ideas what it is?

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Brushbuffalo
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PostSat Apr 11, 2020 10:50 am 
My first wild guess is it is fragmented granitic rock. If so it would have been busted up by faulting, or perhaps by intrusion.
I'll be back in this one.
EDIT: no further info hit my noggin, other than that a glance at the Geologic Map of the North Cascades (USGS Scientific Investigation Map 2940) shows the  most likely rock association is mapped as "Tcas, intrusive rocks of the Snoqualmie family" (Miocene and Oligocene), having crystallized between 22 and 28 million years ago.

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Jake Robinson
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PostMon Jun 01, 2020 8:53 am 
Interesting layers/folds in the rock here. Taken from Diamond Peak in Idaho's Lemhi Range. Sorry the photo is kind of blurry but it was pretty impressive in person.

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