Aluminum Foil Rock? Help on best guess

NevadaBill
fully equipped rock polisher

Member since January 2019
Posts: 1,332

Aluminum Foil Rock? Help on best guess Apr 24, 2020 18:55:45 GMT -5 RickB, rockpickerforever, and 1 more like this

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Post by NevadaBill on Apr 24, 2020 18:55:45 GMT -5

I was walking along the shores of the Colorado River today looking for new rocks to adopt, and ran across this guy

It has flecks of aluminum foil looking, highly reflective something embedded throughout the rock.

So I hit it with a hammer hard, and broke it into 3 pieces.

The rock is solid on its own, but appears to be a conglamerate with flaky pieces of metal looking stuff inside

The metal looking stuff is not magnetic at all

The metal flakes are almost like very thin layer upon layer of thin metal

When taken off, the flakes are NOT transparent. They appear to have a backing or something.

Flakes can come off easy (knife)

Here are some photos of the rock

1)

2)

3)

4)

5)

6)

Now, at first I thought this was glass. I live near a site where there was much sand / silica, which was struck by lightning (someone told me this), which turned it in to flaky chunks of glass. The glass is also highly reflective. But upon closer inspection, you can see through it, and it is just the glass which is reflective.

2 photos of the glass rock from a different site (not related to rock in question today)

NOT SAME ROCK 1)

NOT SAME ROCK 2)

Try not to confuse the prior two photos with the rock in question. They are of different rock, from different sites.

One last close up look at rock in question:

Again, the thing that keeps me thinking that this worthless piece of rock is metalic, is that I can peel off little slices of the layers with a knife. And each slice seems to have a backing to it. It is completely reflective on its own, on both sides. And not transparent like glass.

Looks like Aluminum Foil embedded in a 200,000 year old rock. Maybe cave men (and women) used Aluminum Foil when cooking?!?

Anyone want to take a shot at it? Thank you!

~ Bill

rockpickerforever In Memoriam RIP Jean Bradley, you are forever loved Member since July 2011 Posts: 12,069	Aluminum Foil Rock? Help on best guess Apr 24, 2020 18:59:57 GMT -5 mohs, RickB, and 4 more like this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by rockpickerforever on Apr 24, 2020 18:59:57 GMT -5 Looks like mica in the first rock, Bill. The second rock is most likely gypsum.
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mohs
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Aluminum Foil Rock? Help on best guess Apr 24, 2020 19:02:33 GMT -5 RickB, fernwood, and 3 more like this

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Post by mohs on Apr 24, 2020 19:02:33 GMT -5

i forget the name
and from a jus a picture
it would be a shot in the dark

but there is type of mica rock
that pioneers used for windows panes
probably go back even
1000 years

dazagneiss

hummingbirdstones
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Aluminum Foil Rock? Help on best guess Apr 24, 2020 19:03:00 GMT -5 RickB and NevadaBill like this

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Post by hummingbirdstones on Apr 24, 2020 19:03:00 GMT -5

Looks like Mica to me. (what)

Robin

"Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive. It would be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated; but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience."
~ C.S. Lewis

It's a long way down the rabbit hole, Alice. ~ Ren

rockstock
spending too much on rocks

Member since April 2019
Posts: 472

Aluminum Foil Rock? Help on best guess Apr 24, 2020 19:04:30 GMT -5 via Tapatalk hummingbirdstones, NevadaBill, and 1 more like this

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Post by rockstock on Apr 24, 2020 19:04:30 GMT -5

Mica for sure, it has a neat look to it. Some of the landscape rocks I've been using as filler have quartz and feldspar with mica portions that smooth out and keep that reflective metallic luster.

wpotterw
spending too much on rocks

Member since September 2016
Posts: 450

Aluminum Foil Rock? Help on best guess Apr 24, 2020 20:00:15 GMT -5 fernwood, NevadaBill, and 1 more like this

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Post by wpotterw on Apr 24, 2020 20:00:15 GMT -5

Apr 24, 2020 18:55:45 GMT -5 NevadaBill said:

I was walking along the shores of the Colorado River today looking for new rocks to adopt, and ran across this guy

It has flecks of aluminum foil looking, highly reflective something embedded throughout the rock.

So I hit it with a hammer hard, and broke it into 3 pieces.

The rock is solid on its own, but appears to be a conglamerate with flaky pieces of metal looking stuff inside

The metal looking stuff is not magnetic at all

The metal flakes are almost like very thin layer upon layer of thin metal

When taken off, the flakes are NOT transparent. They appear to have a backing or something.

Flakes can come off easy (knife)

Here are some photos of the rock

1)

2)

3)

4)

5)

6)

Now, at first I thought this was glass. I live near a site where there was much sand / silica, which was struck by lightning (someone told me this), which turned it in to flaky chunks of glass. The glass is also highly reflective. But upon closer inspection, you can see through it, and it is just the glass which is reflective.

2 photos of the glass rock from a different site (not related to rock in question today)

NOT SAME ROCK 1)

NOT SAME ROCK 2)

Try not to confuse the prior two photos with the rock in question. They are of different rock, from different sites.

One last close up look at rock in question:

Again, the thing that keeps me thinking that this worthless piece of rock is metalic, is that I can peel off little slices of the layers with a knife. And each slice seems to have a backing to it. It is completely reflective on its own, on both sides. And not transparent like glass.

Looks like Aluminum Foil embedded in a 200,000 year old rock. Maybe cave men (and women) used Aluminum Foil when cooking?!?

Anyone want to take a shot at it? Thank you!

Quartz and muscovite mica

pauls fully equipped rock polisher Member since May 2013 Posts: 1,173	Aluminum Foil Rock? Help on best guess Apr 25, 2020 2:31:14 GMT -5 fernwood, NevadaBill, and 1 more like this Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by pauls on Apr 25, 2020 2:31:14 GMT -5 As others have said, Mica, probably Muscovite Mica, not metallic at all. Other is Gypsum.

Benathema
has rocks in the head

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Aluminum Foil Rock? Help on best guess Apr 25, 2020 2:42:21 GMT -5 fernwood, NevadaBill, and 1 more like this

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Post by Benathema on Apr 25, 2020 2:42:21 GMT -5

Mica. Find it all over Colorado. I have a few "books" of it. Supposedly, if you're finding mica in an area, there's a chance other minerals may have crystallized in the area.

rockpickerforever
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RIP Jean Bradley, you are forever loved

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Aluminum Foil Rock? Help on best guess Apr 25, 2020 13:04:14 GMT -5 mohs, NevadaBill, and 1 more like this

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Post by rockpickerforever on Apr 25, 2020 13:04:14 GMT -5

From Southern California, the land of pegmatites! Quartz, mica, beryl, schorl and various other flavors of tourmaline found here.

I have a large rock in my front yard, collected on a field trip with my previous rock club, into the mountains just east of San Diego. We had actually gone for lepidolite (got some of that, too), and it is now in the yard as well.

And clear sheets of selenite, a variety of gypsum. Gypsum, selenite, and calcite all closely related minerals, composed of calcium sulfate.

These are all old photos. The selenite (or whatever the purists would call it) was found out at my favorite rock haunt, Ocotillo Wells.

Jean

Last Edit: Apr 25, 2020 13:05:36 GMT -5 by rockpickerforever

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NevadaBill
fully equipped rock polisher

Member since January 2019
Posts: 1,332

Aluminum Foil Rock? Help on best guess May 16, 2020 9:03:44 GMT -5 rockpickerforever and RocksInNJ like this

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Post by NevadaBill on May 16, 2020 9:03:44 GMT -5

Thank you for all of the replies folks. Mica and Gypsum / Selenite it is. Definitely.

Thanks rockpickerforever for the fantastic pictures. I am jealous of your Mica samples. They are so nice. I especially love the one with the blue/green crystals running through it.

I guess in the Desert Southwest, this mineral is about as common as you could get. Somehow I have only stumbled on one sample myself. I can't imagine where its origin might have been, really. Not being an earth scientist and all.

Even though I don't collect minerals really and my sample is dwarfed my your colossal front yard specimens, it is unique to me and so it sits in a nice desert cactus garden located in one the courtyards.

Thank you all for solving this mystery for me!

~ Bill

Peruano
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Aluminum Foil Rock? Help on best guess May 16, 2020 9:47:51 GMT -5 mohs and hummingbirdstones like this

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Post by Peruano on May 16, 2020 9:47:51 GMT -5

The old timer name that Mohs was searching for is isinglass (i.e. mica sheets). Not to be confused as Wikipedia does with the stuff made out of fish bladders the brewing process.

Tom
Combining bicycles, trailbikes, hiking, and rockhounding as a justification for enjoying the fresh air of New Mexico.